Another High Idle 3.0 thread

[Ahlem]

In working through the new to us 1993 3.0 automatic, the latest issue seems to be a high idle and erratic hunting after coming off the freeway occasionally. There was a fair amount of effort put into cleaning out the fuel system but not the TB or idle air control or MAF/AFM(?) just yet.
The idle stop screw on the lower side of the TB has a paint dot on it that looks original and other than it appears to be a PITA to loosen and adjust the lock nut and stop screw, I think it's probably something else causing the issue.
I haven't checked the timing yet either. Any suggestions? I plan on starting with Carb cleaner at the TB first.

 

[Ahlem]

Here's an update.
I made this after a visit to the local LKQ. The crimp on butt connectors are crimped just enough on the open end to hold my multi meter probes nicely.
I adjusted the TPS properly. I was having trouble keeping the probes in good contact in the very cold weather here. I then broke out my 1973 vintage timing light and "discovered" someone had set the timing at 18 degrees or more BTDC. After I put it at the specified 10 degrees, it runs way better and closer to reality. It will get a couple days of test driving to see if it needs further help.

 

[LedFloyd900]

Did adjusting the TPS cure the high idle? Mine does the same thing and adjusting that is one of the many things on the to-do list

 

[Ahlem]

Between adjusting the TPS and setting the timing, major improvement occurred. It's still surging after coming off the expressway when I shift to Park when I get to work. I need to check the fuel pressure due to possible clogged fuel filter issues. See my previous thread on what we found and running on 3 cylinders.
I may have a rusty gas tank but haven't been too anxious to drop the tank with the sub zero weather we've been having for a good part of January and February. I also discovered a nice sticker under the hood that has the EGR hose routings so I can double check to see that I didn't get something reversed when I had the intake plenum off.

 

[Ahlem]

Another update...
The surging idle is now gone I think the TPS adjustment and timing adjustment took care of that problem. Last week when it was 50 degrees F outside, the car idled too low and I had to adjust it upwards to get to 800rpm. We had a big temperature swing and it was back to 1200 rpm at 25 degrees F. I'm leaning toward a temperature sensor issue. How many temperature related sensors are there on a 3.0 and where are they located? I'm thinking there is a coolant temperature sensor, an idle air control sensor and possibly a temp sensor in the AFM area some where?

 

[flyinhawaiian01]

Yes, there is an IAT in the MAF sensor, see the pinkish-colored wires in here?

That goes to the IAT. I don't recall if there's another one somewhere else, just drawing a blank right now for some reason! Guess I have too many other things going on in the shop today...:lalala:

 

[Ahlem]

So is the Idle air temp sensor thingie serviceable or can be checked for proper function?