Rough idle after highway driving?

[cp2295]

got a 99 3.0 manual. After driving on the highway for a while and putting it into neutral it will sometimes start wanting to die. Also if i'm in neutral and i turn then it will do the same (not all the time though, just sometimes), and i've had it die on me a couple of times. i haven't checked my fuel pressure yet, but i'm thinking it could be something to do with fuel/air delivery.. maybe some sort of sensor? i don't know, give me your thoughts..Thanks!

 

[Earl43P]

The IAC controls idle.

Remove it (two 8mm bolts) and clean it with a solvent.
Whack it against your hand so the plunger slides along that shaft and makes a thwock sound, repeatedly, with solvent in it while covering the ports.

Force it to relearn idle by disconnecting the battery, turn on/off headlamps, reconnect.
Idle for 4 minutes in each of these:
Park or Neutral
Drive with brake on
Park or Neutral with AC on
Drive with brake on with AC on

The 2.3 and 2.5's have a power steering pressure switch that signals the PCM to increase the idle, using that IAC. V6's don't have that pressure switch because they should compensate without that trigger (they have more power).

The computer learns to compensate for a bad/sticky IAC. You can see that by looking at the short term fuel trims with a live scanner (like a ScangageII).

 

[snake]

If no code, IAC. If it throws a lean bank code it might be a vacuum leak. Check your PVC line for a rubber boot with a hole in it, most likely leak.