Well if its the same as before than i wouldnt adjust it, and because its a 88 i dont know if you can. Only thing i could think left of testing for codes, and possibly the actual wire harness for the IAC or TPS is bad and you have little or no electronic signal.

 

I'm feeling it may be possibly a blown intake gasket causing a vacuum effect when the martial or crack in the gasket expands when it gets warm. Easy and cheap to fix and not out much if that's not it.

But coding it is where Id start.

 

I was thinking intake or even throttle body gasket too, but it would be also doing that when he was driving and idling, even if it was warm. Still wont hurt too look.

 

How can I check the harness at the iac and tps?

 

I can't get the codes because when i grabbed the wires they fell out of the connector. Now I don't know which slots they go back in.

 

Check along those wires for broken wires, dirty connection etc. As for the diagnostic connector and the wires falling out, someones gonna have to post a pic of that cause i have no idea how they go back in.

 

Check your throttle body gasket next.

 

Use starting fluid to check for vacum leaks. I'd start with the plastic vacum lines they are more than likely to be the culprit. I fought this a couple of weeks ago. Found that the rubber hose going to the Pcv valve was dry cracked along with a couple of the plastic lines that were sucking air. Inadequate vacum will throw off the the map. It is located on the passenger side of the firewall above the blower box.

 

Replace

 

the throttle body gasket melted on my 4.9l and was also part of my problem so, yes check that too.