New stealth owner. 91 stealth RT 5spd, when the car is at running temp,, the normal running temp. my idle dropes to 500 rpm or less. gotta keep my foot on the gas to keep it from stalling, i checked the air filter and i have put clean high test gas in. with some throtle body cleaner, and still does it. i am waiting for the shop manual to come in and the guy i bought it from did play with the timing and idle screw witch i put back to the origanal settings. fixed most of it but still does it. just wonder would it be the fuel filter and where is it..lol i only had the car for 4 days now love it when it runs smooth,,


oh and its a rebuildt motor and trany, with new clutch.. great shape for wat i paid for it

 

could be the MAS, have it checked.
the fuel filter is located on the firewall right below the battery i think, its a black cycle type thing, kindof looks like a oil filter.

 

This could be so many things. I have been having this exact same problem with my stealth. I replaced the IAC, Put new fuel filters in, and Even purchased a new ECU and none of it has worked yet! Hopefully it is not your ECU because those can get expensive. I honestly would start by taking it to a mechanic if you have the money for it and maybe he can run a scanner on it to see if its throwing any codes. Otherwise i would start with your IAC valve being that its a common culprit for breaking. IAC valves for stealths run around a 100 bucks at oreillys