Chrysler Repair: 89 Dodge Spirit LE Automatic Turbo 2.5L 4 cyl 113k, air control valve, cross shaft

Question
Thanks for helping me with my previous question.  Recently replaced MAP and HEP.

Car dies after starting it up.  It sounds rough, like its going to die.  Can hear it is trying to remain running but slowly dies.  After starting it again it wants to die, but I press down the gas.  The rough idling goes away after driving it for a little bit.  This happens after its been warmed up.  Doesn't happen when its cooled down.  Also not sure if this has anything to do with it dying.  When first turning my car on after it has been running for several hours the RPM's go between 1250-1500.  Pretty that is too high.  Wondering if the Idle Air Control Valve is causing this issue.  Perhaps throttle body?

Check Engine code 12 & 55.  55 doesn't mean anything.  Curious why 12 hasn't disappeared after turning the car on after 15 times of turning on the car.

Answer
Starting with the last part first, 12 and 55 will always come up when reading codes on an older vehicle. 12 indicate the start and 55 represents the end. It wouldn't be a bad idea to remove the throttle body and give it a good cleaning, pay close attention to the areas closest to the cross shaft. I'd also take IAC out and clean the tip off as well as the air passage. A sticking IAC could very well cause the excessive idle concern also. You should also check all the vacuum hoses, especially those that run behind the valve cover, they had a tendency to crack witch would cause some driveability problems.