1st gen probe problems...

i got a 1989 ford probe gl 2.2 liter engine auto. 70k miles on it sat for about 2 years. i got a tune up on it, but when i first start driving and i come to a stop.. the rpms drop to below 500 and the car starts to shake like its gonna cut off. only happens like 1 or 2 times after the initial start after the car warms up, even a little, it doesnt happen. second thing is when i come to a complete stop, i can tap the gas and put the break on, my rpms will shoot up like any normal car, but then they will drop to around 300, and sometimes the car will even stall completely, i have ran 2 bottles of fuel injector cleaner through the tank and it still happens. im clueless. ive put about 2700 miles on the car so far, seems to run fine, but then those 2 things happen everyone once in a while. any advice?

Have you checked the air tube from the air filter box to the throttle body for cracks.That caused mine to do the exact same thing.the part cost about $60 though.