I posted in the general section, and was told to post here....I have a 86 TA, 305 5spd. 153,000 miles. Everything was original on my car-carb, etc. I noticed one day while driving that the idle was staying around 1100-1400 rpm...and if I kicked the gas, it would idle back where it was supposed to be around 700rpm. So, I decided to see if I could do some adjustments and get it to work. After working with it for a week, it was still doing the same thing and said well maybe it's time for a new carb. I went to the local auto parts store, who sells the Rochester Carbs all rebuilt...same thing as mine just new. Got one and put it on. Couldn't get my cold idle cam to work like I wanted and I didn't have enough knowledge on how to do it....so I brought it to the local mechanic who's worked on these for a long time....he actually does a lot of work on non computer controlled carbs...but knows his stuff.
He did my timing, that was off. The problem now is that when you start her cold, she'll start idle at 1800rpm and then die out within 20 seconds. The you refire her and she'll go up to 1800 and then start searching for the correct idle, up and down between 1800-800rpm. Then you go to go and you step on the gas, but she bogs and all of a sudden will take off. Once she is hot she'll start will no problems and run really well, except she will start to high idle again around 1100rpm, when you have to stop or push in the clutch. If you hit the gas, tap it, she will come back down and idle at 700rpm. In the driveway, I took the air cleaner off and watched what the carb does when it sticks. If you lightly touch the gas to move the car and then stop the throttle body will stick maybe 3/16" up from the curb idle screw. If you hit the gas, like a really fast tap on the peddle, the throttle body will come right back down and rest on the curb idle screw. When sticking you can push the throttle body back down to hit the screw, but sometimes it's not that easy to push. I have 2 return springs on the car and they are not weak....The mechanic is even stumped and doesn't know what's going on with it.
So, carb guys, I need some advice......I don't have my original carb as I had to turn it in for the core charge.
HELP!

 

When you say "throttle body", I'll assume you mean the throttle arm.

Take the throttle cable off the throttle arm and see how it behaves. You probably have a sticky throttle cable.

 

It sounds like you have two problems:
1. Choke set improperly- check vaccum break and fast idle screws
2. Throttle linkage/lever is stuck or your accelerator cable is binding. Check the accelerator cable and maek sure it moves freely. If it does not, get some cable lube. The the throttle lever is sticking, try some graphite grease around the fittings(don't use a wet grease).