Any ideas? Engine dying in drive

[MattPro]

I was wondering if anyone might have any insight into what might be causing this problem. I just completed a head swap after my timing belt broke, and replaced a lot of the stuff along the way. Just finished it today, and the car started up right away and was running fine.
After driving for about 20 minutes I started running into problems. The car idles fine when in neutral or park (it's an auto), but as soon as it is put into any gear (drive, reverse, 1, 2) the idle gets really rough and unless you give it gas to start going right away it dies. It does seem to be driving normal when giving it gas or driving at speed. If I'm driving and get to a red light and stop, I have to put the car into park or else it the RPMs start spiking and the car like tries to lunges then dies right after.
After it dies it takes a couple attempts to start again. I can leave the car and park and start it and it will idle fine for 10 minutes, I can then turn it off and start it again and it starts beautifully. It's just after it dies it doesn't want to start.
Basically I'm just trying to figure out where to start looking for problems with this. Thanks for reading!

[b*saint]

Prob a vac leak.

[MattPro]

Prob a vac leak.

That's what I was thinking, but wouldn't a vacuum leak mess up the idle when in neutral as well? It just runs perfectly in neutral and that's throwing me off.

[b*saint]

I dont know. My car idles high and rough so. I think the ICV is trying to keep it in check also.

[jlevie]

That's what I was thinking, but wouldn't a vacuum leak mess up the idle when in neutral as well? It just runs perfectly in neutral and that's throwing me off.

An upset of the A/F ratio, improperly timed cam, etc., will rob the engine of power. The load of the torque converter when the transmission is in drive can be enough to make such a problem obvious when it isn't when that load is removed.

Start by a complete check for intake leaks, which means a smoke test of the intake. Once intake leaks have been ruled out of fixed other possibilities can be investigated.

[MattPro]

An upset of the A/F ratio, improperly timed cam, etc., will rob the engine of power. The load of the torque converter when the transmission is in drive can be enough to make such a problem obvious when it isn't when that load is removed.

Start by a complete check for intake leaks, which means a smoke test of the intake. Once intake leaks have been ruled out of fixed other possibilities can be investigated.

Thanks for explaining that, that really makes a lot of sense now.

Also just as an update I had an extra ICV laying around so I threw it in and the car didn't die once on me for probably another half an hour. After that... 4 times on a 5 mile drive at stop signs...

[warmsquash1]

Might be that the valve has a cracked boot or is sticking. Kind of rare for two to do it back to back if it's sticking though... I would say smoke 'em if you got 'em... If not then if you're careful (This is UBER dangerous, but I've done it in a pinch when there's no smoke machine available) shoot a couple of shots of ether around the vacuum connections. NOT A FULL STREAM!!! Be aware of where any electric/ignition components are and stay away. It works good because the engine will rev up when the vacuum leak sucks in the ether. If you're safe about it and do it outside then you'll keep the hair on your kiwi's....