1990 toy corolla idle is rough can feel it through steering wheel. when cold car idles good as it warms up it gets rough. tune up good. mounts good that was one of the first things i checked. checked vacuum valves. hoses good. pcv good . air filter good i have ran out of ideals. please help.

SOURCE: 97 Camry Rough cold idle, weak accelleration and noisy exhaust

Lots of times the idle air control valve gets stuck on these engines. You can try cleaning it. Remove the air intake hose from the throttle body. Start the engine and spray throttle plate cleaner through the hole in the bottom on the throttle body. This will run the cleaner through the idle air control valve. make sure to keep the RPM's at about 2000 to 2500 throughout this procedure. You may need to install a new idle air control valve if it continues to happen.

SOURCE: Intermittent rough idle on 2002 toyota highlander

before you do this I would get some wooden qtips - the long ones auto detailers use. take off the air filtrer assembly and spray carb cleaner into the air\fuel intake and use the qtip to wipe out the inside of the intake. I had the same problem with my highlander a year ago and this fixed the problem.

SOURCE: 1990 celica 2.2 5s-fe wont idle, wont erach 1400rpm

your problem is in your throttle sensor that controls the idle it is located right behind your intake and it has two screws that mounts it i am almost positive that this is where your problem is comig from