High rpm when idle, but only after driving

The equipment:
1995 Buick Regal Custom 3.8

I have this really strange problem that I cant seem to figure out. Maybe someone can provide some insight to this.

I noticed a year ago that my car would randomly stall out coming into work after a 20-25 minute drive. It then started to idle really high, very rarely. So i cleaned the throtle body, new air filter, new fuel filter, sparks, and wires. This is about where my expertise ends.

Its seemed better, however, it would act up now and again (stall) but I was fine with it.

Recently I have noticed that the car idles really high 1.5 in drive (compared to 900) and 2k in park after I have drove for 20-25 mins. So I put the computer to the car and all I have is transmission error codes which I have had since I owned the car at 80,000 miles and I am now to 160,000 miles. This car has been pretty good to me because it starts, goes forward, and backwards! What else can you really ask for. A better idle maybe?

Thank you for any help you can provide.


What transmission codes are you getting?
They could point to the idle problem.

Cleaning the throttle body was the only thing that you did that could have cleared up the fast idle issue. Everything else had no chance of clearing up the high idle problem, though the car probably dearly needed attention. You’ve been living with this for a year now and letting an issue fester is the biggest mistake.

You say the car has been good to you, but you need to be good to the car and fix an issue when it arises.

Post the codes and maybe someone here can help you.


Your high idle could be attributed to a cracked vacuum line or a bad IAC (Idle Air Control Valve). I would check for a vacuum leak (highly likely) and if you can’t find one…replace the IAC. I know some people clean them but on a 20 year old vehicle…I would just replace it. I say the vacuum leak is highly likely because some components of your engine do not utilize vacuum until the engine is heated to normal operating temperatures.

I have found some decent documentation on where the vacuum hoses are located, but I feel uncomfortable doing this already. I will either just tell a shop mechanic to replace or get my sucker brother to do this Halloween in exchange for a steak.

Most likely going to change the vacuum hoses and see what happens from there. The IAC would be a very easy fix for me to do later if I dont see any improvements.

BTW, my car no longer stalls. Replacing the parts I listed above did help resolve the stalling issue. Also, as far as I can remember the transmission errors code had to deal with a torque converter sensor. There was another predominate one, but I cant remember.