2.3L ('83-'97) High idle issue

[750beater]

Alrighty guys. So I got the 2.3 Lima. Manual Transmission Truck runs awesome! BUT a year or so ago I kept having idle issues where it would rev to like 2,500-2,800 rpm's. But then it would drop less then idle. I had scanned it and of course no codes despite it running like that for a while. So I just bought and IAC valve. It immediately made it idle normal. And for the most part it was. The low idle has never can back. Well the high idle has slowly came back. It is more common when it is warm or hot outside. When I go into neutral it revs up and won't stop until I basically come to a complete stop. One interesting thing is when it is reving, if I shut the truck off for like 10-15 seconds, it will idle totally normal after turning it back on. So tonight I plugged my scanner in, (my CEL bulb has never worked) to see if there are more codes. Well I have 4. But IMO, correct me if I'm wrong but none of these would directly cause high idle. I plan on cleaning my throttle, egr tube, and check all my vacuum lines this weekend. But I'm sure someone has had a similar issue. I'm going to reset the codes with the scanner and see who comes back first.

Codes
P0401 EGR bad flow (Edit I changed the EVR sensor a year ago and that code went away but I do not know what code it had said.)
P0802 lean/rich code? Maybe idle issue?
P1086 O2 sensor fault?
P1443 Purge valve code

 

[franklin2]

If you get a lean code it could be from a vacuum leak. The purge valve could be the source of the vacuum leak. I think I would plug that valve off temporarily and see if the random high idle went away. If it did, I think I would replace that valve or look into the evap system and why it's giving you the valve code.

 

[tomw]

Dunno about the codes, but I would clean the IAC. And the throttle plate/body. They can get gummy and not work too well.
tom