Mitsubishi Repair: Flat spot on GTO VR4, hesitation problem, emission control system

Question
Hi Linda,
I have a flat-spot (Hesitation) problem with my car at around 800 to 1800rpm. Performance beyond 1800rpm is fine. The curious thing is that when I remove the plug on the MAS sensor the flat-spot diappears, however the CHECK ENGINE light comes on and idling is very erratic.

I have replaced the air filter and checked wiring overall to no avail.

Would appreciate receiving your expert advise as to what may be causing the problem.

Answer
Anthony: I think you should remove the plug on the MAS sensor but have the car coded then to see what the computer will kick out at you. It could you that you have a weak sensor someplace, as the computer takes all its readings from all the sensors through out your car's engine and then sets up how things should run. But if something in the way of a weak sensor; the computer does not always pick up on this. So it might cause the flat-spot. Or you could have a vacuum leak someplace too. Got to ask this when is the last time you did a tune up on the car? Could be the emission control system is not functioning properly that is out of my repair manual. Look this is only ideas for you to check. But coding your car the computer might kick out the problem. How about this try taking the neg cable off the battery, wait 5 minutes and put it back on. That should reset the computer and maybe it will clear whatever is bothering it. Sometimes that does work. Other wise you will have a shop check out your problem. Hope this helps some and good luck! Linda