I thought this problem was just going to go away but it still persists.

Originally, after I replaced timing belt and did all that good stuff, when I start the car it idles high (1500ish) then after 10-15 seconds drops down to 800ish. It only did that a few times.

Every single time, after I drive the car and then put it into park (when I am done driving it - could be after 10 minutes or 30 minutes) it starts at around 1500ish then drops down to 800ish after a second, then jumps back up to 1500ish and back down again. It continues to do this. I am not sure how long it lasts for - longest I have let it sit is about 7-10 seconds. After a week of driving it every day it's still doing that.

Also, when the car goes from 3rd to 2nd and then 2nd to 1st gear (if I am stopping for a red light for example) it jumps from 800ish to 1500ish RPMs. I imagine going down a gear would increase the RPMs however it feels like someone tapped the gas (I didn't) and jumps forward a little.

Any thoughts? Its an automatic and I've replaced several things on the car after it died on me. There's a bit of history with it if it helps. Thanks.

 

Check the IACV and if its dirty clean with Carb cleaner.

 

Is it safe to assume there's no good way to check if it is dirty without taking it out? lol After reading on what the IACV is, makes sense now that that is what the issue could be. I will do that either tonight or tomorrow. Thanks.

 

I checked the IACV and it was a little dirty. I didn't take it all the way out, I only un-did the two 12 mm bolts and I used Brake Cleaner instead of Carb Cleaner. It certainly looked better, and since I was in a hurry I couldn't let it sit for the full 15-20 minutes - more like 5 minutes and wiping it off with a rag.

Anyway - both problems still persist. Should I try again using Carb Cleaner and actually taking it off all the way or is there something else that is wrong? Thanks.

 

Any more thoughts? Thanks.

 

Alright well I completely took the IACV off this time, even though it looked clean for the most part I went to town on it. Cleaner, rags, can of air, the whole 9 yards. If it wasn't for being 17 years old - it would look as good as new

Anyway - I drove it for about 20-25 minutes, on street and on highway - and put it in park and it definitely did not fluctuate the idle like it did before. However, it is still feeling/acting/sounding weird when it goes from 3 to 2 and from 2 to 1.

This is an automatic. Should I be using D3 or D4 for the most part? I've been driving it in D4 all the time but since about 3-4 days ago, I am driving in D3 if I don't need to go over 40 mph. Thoughts?

EDIT: Here are some pics of the IACV after cleaning.

 

Update - I was wrong with my previous post. I drove it to work this morning and put it in Park and the same thing happened with the fluctuating idles. Any thoughts?