Have. 90 2 dr and getting very frustrated with it . I've had this issue for awhile now and it stopped for a couple of days and then did it again . Ive replaced the tsp sensor cleaned iac sensor haven't replaced CPs sensor yet but if I stop and put it in park and keep on the gas around 1100 to 1400 rpm it sometimes decides to go back down and idle normal . I've gone over the vacuum lines and can't find anything . I've done the starting fluid or brake cleaner trick and found nothing maybe need to test the lines some way for pressure I'm so confused on why it won't idle in park neutral and drive or reverse after it warms up any help would be appreciated

 

Got a multi-meter?

Did you adjust that TPS?

Test the sensor ground circuit?

Ever refresh your grounds?

 

What do you mean refresh grounds ? By cleaning them up new wire if needed kinda think I get what your saying I don't believe I adjust the tps sensor I do have a multi meter just trying to find is the question lol

 

Everything you need is in the "pink link" in my signature below. With photos.

At a bare minimum, you need to do #1, 3, 5 and 8.

And you MUST invest $10 in a multimeter. We'll walk you through all of this. It's very easy and you'll learn alot.