85 Cimarron-fast idle at startup

My 85 Cimarron has 70,000 miles. When I start it cold it starts idling at about 2000 rpm and then goes down to about 1400 rpm after about 1 minute then takes about 5 minutes to go down to about 1000 rpm. Then when I push on the brake to shift in to gear the rpm increases to about 1500 rpm and then takes a couple minutes to come back down to 1000 rpm. Any ideas? Easy/cheap fixes?:banghead:

Dirty throttle body can cause this. Clean the throttle bores and plates with O2 sensor safe carb cleaner and a toothbrush. Disconnect then reconnect the negative battery terminal to reset the computer. Worth a shot.
FWIW
YMMV

Look for a vacuum leak in the intake manifold. Suck a leak allows extra air into the engine, just as if you have your foot on the accelerator.

IMO take a look at the vacuum brake booster first.

Try removing and plugging the vacuum line to the booster (don't drive it!) and see if the problem persists.

do you know if they have liquid cooling system in cars