Mitsubishi Repair: 1994 eclipse, mass air sensor, barometric pressure sensor

Question
1994 Mistsubishi eclipse 1.8 manual.  I have a check engine light and the codes are 13(intake temp), 25 Barometric sensor, 21 coolant sensor. The engine would not idle. I adj idle screw and now it will idle, but when it is cold it is very hard to get to start and run until it warms up.  This sounds like temp sensor problems but the all check within spec.  I am at sea level if the baro sensor failed it would run ok or to very rich.  The care  appears to be running lean.  Any ideas?

Answer
Rick,
There may be an overall problem with your Mass Air Sensor (MAS).  Your MAS, which is in your air filter can, may have had it's harness disconnected.  Make sure the harness is securely seated.  If it is, remove your MAS and on there you'll be able to check both your IAT and barometric pressure sensor.  If you have a service manual for your car, they will give good detail on how to check these sensors with a voltmeter.  You should also inspect your Idle Air Control (IAC) motor.  Sometimes it can cause your IAT and barometric sensor to throw codes.  

If you checked all those items and still can't find the problem, check your car's computer.  Read this article for futher information:
http://90gsx.com/eclipse/cap/caps.htm

If your ECU is malfuctioning, it can throw all sorts of strange codes and cause strange idle and starting problems.
Good luck!