Mitsubishi Repair: Problem Idle Issue cold driving and Engine Noise 1996 Mits 3000GT VR4, throttle position sensor, timing belt tensioner

Question
I own a 3000GT 1996 VR-4 (6speed, manual, mods include. 3sx down pipe...K & N intake and Borla Single exhaust)  Need help the care has a few issues.  Active Aero system shuts off after  system retracts below 30mph.  Aero light comes on.  The front spoiler frame moves with my hand.  If I push it up straight the system works again until it retracts then the light comes on again.  The plastic airdam is broken and was apparently hit by the previous owner.  I need help their, just want to fix it without having to replace the $430 front spoiler.  The most concerning issues are with the idle and cold start drive of the car.  Let me give you a little background information.  I bought the car 3 months ago with 96,000 miles on the car.  Love these cars!!  This is a list of all the new or rebuilt items on the car. New transfercase, drive line, clutch and flywheel, rebuilt 6 speed tranny 10K miles of use, new timing belt, tensioner, fuel pump, new AC system with new compressor, 2 new wheel bearings.  Now the bad! The car seems to have an idle issue.  The person I bought the car from told me about the check engine light the recently came on explained that it was a mass airflow sensor...Great Not I'm sarcastic that's a $599 part.  I took the car to the dealership.  They fixed a few issues and the check engine light turned out to be a Throttle position sensor which he adjusted resolving the check engine light problem.  Now a couple days later I am having idle problems the car sputters and stalls on cold starts and during the initial drive. Driving a short time resolves the issue.  The check engine light is off but it has started and then stalled or had trouble maintaining idle.  If I gas it a bit the idle will return near steady.  I filled the tank with Premium fuel system cleaner with octane boost.  Then last night I started and drove the car and it seams fine.  Before you chime in with your answer I have one other issue.  2 nights ago after driving most of the day, I parked my car and heard a disturbing noise coming from the passenger side engine bay center of the V in the engine.  I video taped the engine and sound for my mechanic visit next week.  It sounded like an off balance loud wobble in the engine.  Thinking that it was the crank shaft, bearings or balance bearing I got alittle scared. I wish I could upload the audio.  What do you think could be the problems???  I hope I don't have to rebuild this motor!


Signed

Eric
Concerned and Confused Proud VR4 Owner

Answer
Eric: Who replaced the timing chain, the guy that owned the car before you or a shop? I would be checking that work, could be the balance shaft belt is bad or the balance shaft tensioner. Look I would have replaced the sensor that was in the Throttle position sensor. Because with time, you will have to replace it. You can only adjusted the throttle so much. That sensor is not sending the computer the right read outs and so the computer is not setting the engine up right. Sometimes you can have problems in the system but the computer does not kick that light on. Might check the engine mounts on that side maybe one is broken or loose. Or it could be that balance shaft that I talked about. Sometimes people will replace the timing belt but not replace anything other parts there. You have to wonder why that old owner did so much work on the car but then sold it.Does the car heat? Use water? Blow white smoke? Then hey you are lucky if it is not doing that because that would be a blown head gasket. I always do a good tune up on a car when I first buy it. I know the guy replaced all those parts but a good tune up does wonders. But still my friend, people always think the worse on these engine sounds. You need to wait on your machanic to see what he thinks it is. I do hope things turn out well for you. Remember though Eric replace that sensor in the throttle because other wise down the road you will be doing it anyway. Trust me, I know. Oh hey don't tell your machanic that you got your ideas from a woman on line. It will not sit well with him. lol. Hope this helps some to easy your mind and God bless: Linda