diff --git a/js.go b/js.go
index 429959d92..d6d4b5463 100644
--- a/js.go
+++ b/js.go
@@ -332,13 +332,21 @@ func ExpectLastMsgId(id string) PubOpt {
 // MaxWait sets the maximum amount of time we will wait for a response.
 type MaxWait time.Duration
 
-func (ttl MaxWait) configurePublish(opts *pubOpts) error {
+func (ttl MaxWait) configureJSContext(js *js) error {
+	js.wait = time.Duration(ttl)
+	return nil
+}
+
+// AckWait sets the maximum amount of time we will wait for an ack.
+type AckWait time.Duration
+
+func (ttl AckWait) configurePublish(opts *pubOpts) error {
 	opts.ttl = time.Duration(ttl)
 	return nil
 }
 
-func (ttl MaxWait) configureJSContext(js *js) error {
-	js.wait = time.Duration(ttl)
+func (ttl AckWait) configureSubscribe(opts *subOpts) error {
+	opts.cfg.AckWait = time.Duration(ttl)
 	return nil
 }
 
@@ -487,6 +495,11 @@ func (js *js) subscribe(subj, queue string, cb MsgHandler, ch chan *Msg, opts []
 		return nil, ErrPullModeNotAllowed
 	}
 
+	badPullAck := o.cfg.AckPolicy == AckNonePolicy || o.cfg.AckPolicy == AckAllPolicy
+	if isPullMode && badPullAck {
+		return nil, fmt.Errorf("invalid ack mode for pull consumers: %s", o.cfg.AckPolicy)
+	}
+
 	var (
 		err          error
 		shouldCreate bool
@@ -686,18 +699,6 @@ type subOpts struct {
 	cfg *ConsumerConfig
 }
 
-// Durable defines the consumer name for JetStream durable subscribers.
-func Durable(name string) SubOpt {
-	return subOptFn(func(opts *subOpts) error {
-		if strings.Contains(name, ".") {
-			return ErrInvalidDurableName
-		}
-
-		opts.cfg.Durable = name
-		return nil
-	})
-}
-
 // Pull defines the batch size of messages that will be received
 // when using pull based JetStream consumers.
 func Pull(batchSize int) SubOpt {
@@ -730,6 +731,18 @@ func ManualAck() SubOpt {
 	})
 }
 
+// Durable defines the consumer name for JetStream durable subscribers.
+func Durable(name string) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		if strings.Contains(name, ".") {
+			return ErrInvalidDurableName
+		}
+
+		opts.cfg.Durable = name
+		return nil
+	})
+}
+
 // DeliverAll will configure a Consumer to receive all the
 // messages from a Stream.
 func DeliverAll() SubOpt {
@@ -798,6 +811,55 @@ func AckExplicit() SubOpt {
 	})
 }
 
+func MaxDeliver(n int) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.MaxDeliver = n
+		return nil
+	})
+}
+
+func PlaybackInstant() SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.ReplayPolicy = ReplayInstant
+		return nil
+	})
+}
+
+func PlaybackOriginal() SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.ReplayPolicy = ReplayOriginal
+		return nil
+	})
+}
+
+func RateLimit(n uint64) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.RateLimit = n
+		return nil
+	})
+}
+
+func SampleFrequency(s string) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.SampleFrequency = s
+		return nil
+	})
+}
+
+func PullMaxWaiting(n int) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.MaxWaiting = n
+		return nil
+	})
+}
+
+func MaxAckPending(n int) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.MaxAckPending = n
+		return nil
+	})
+}
+
 func (sub *Subscription) ConsumerInfo() (*ConsumerInfo, error) {
 	sub.mu.Lock()
 	// TODO(dlc) - Better way to mark especially if we attach.
diff --git a/test/js_test.go b/test/js_test.go
index f52466b94..e87e7d5b5 100644
--- a/test/js_test.go
+++ b/test/js_test.go
@@ -211,7 +211,7 @@ func TestJetStreamPublish(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
 	defer cancel()
 
-	_, err = js.Publish("foo", msg, nats.MaxWait(time.Second), nats.Context(ctx))
+	_, err = js.Publish("foo", msg, nats.AckWait(time.Second), nats.Context(ctx))
 	if err != nats.ErrContextAndTimeout {
 		t.Fatalf("Expected %q, got %q", nats.ErrContextAndTimeout, err)
 	}
@@ -220,7 +220,7 @@ func TestJetStreamPublish(t *testing.T) {
 	sub, _ := nc.SubscribeSync("baz")
 	defer sub.Unsubscribe()
 
-	_, err = js.Publish("baz", msg, nats.MaxWait(time.Nanosecond))
+	_, err = js.Publish("baz", msg, nats.AckWait(time.Nanosecond))
 	if err != nats.ErrTimeout {
 		t.Fatalf("Expected %q, got %q", nats.ErrTimeout, err)
 	}
@@ -564,6 +564,66 @@ func TestJetStreamSubscribe(t *testing.T) {
 	}
 }
 
+func TestAckPendingGoesDown(t *testing.T) {
+	s := RunBasicJetStreamServer()
+	defer s.Shutdown()
+
+	if config := s.JetStreamConfig(); config != nil {
+		defer os.RemoveAll(config.StoreDir)
+	}
+
+	nc, err := nats.Connect(s.ClientURL())
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	defer nc.Close()
+
+	js, err := nc.JetStream()
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	_, err = js.AddStream(&nats.StreamConfig{
+		Name:     "TEST",
+		Subjects: []string{"foo", "bar", "baz", "foo.*"},
+	})
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	const totalMsgs = 3
+	for i := 0; i < totalMsgs; i++ {
+		if _, err := js.Publish("foo", []byte(fmt.Sprintf("msg %d", i))); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	sub, err := js.SubscribeSync("foo", nats.Durable("dname"), nats.Pull(totalMsgs), nats.AckExplicit())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer sub.Unsubscribe()
+
+	for i := totalMsgs; i > 0; i-- {
+		info, err := sub.ConsumerInfo()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got, want := info.NumAckPending, i; got != want {
+			t.Fatalf("unexpected num ack pending: got=%d, want=%d", got, want)
+		}
+
+		m, err := sub.NextMsg(100 * time.Millisecond)
+		if err != nil {
+			t.Fatal("NextMsg:", err)
+		}
+
+		if err := m.Ack(); err != nil {
+			t.Fatal("Ack:", err)
+		}
+	}
+}
+
 func TestJetStream_Drain(t *testing.T) {
 	s := RunBasicJetStreamServer()
 	defer s.Shutdown()
@@ -1776,7 +1836,7 @@ func TestJetStreamSubscribe_AckPolicy(t *testing.T) {
 			t.Errorf("Unexpected error: %v", err)
 		}
 
-		err = msg.AckSync(nats.MaxWait(2 * time.Second))
+		err = msg.AckSync(nats.AckWait(2 * time.Second))
 		if err != nats.ErrInvalidJSAck {
 			t.Errorf("Unexpected error: %v", err)
 		}