Mitsubishi Repair: 3000GT VR4 acceleration problems over 4000RPM, acceleration problems, smooth acceleration

Question
Hi there,

Car: 3000GT VR4 1994. It was well maintained: oil, filters, etc.
It idles perfect. Also, when you are not driving and throttle to 7000rmp - no problems engine works smoothly.
But, when driving (in any gear) during acceleration car jerks after 4000rmp and there is no smooth acceleration. No problems if your drive with the RMP lower than 4000. Turbos' effect comes after 2000 and power is increasing up to 4000RPM... Then stuttering and weak acceleration. That happens always: cold engine, wormed engine and in any gear (1,2,3,4,5,6).
What could it be? Have no idea were to start searching...

Answer
Dimitri: Have your car coded, that sounds like a weak sensor someplace. Just not sure which one. AutoZone will code the car for free and that might explain your problem. If not get a repair manual for your car, you would be able to get one at any parts store for around $20.00. It will help you check things on your car. I like Haynes ones the best, they are easy to understand and will walk you through things. I hope this helps and good luck! Also Merry Christmas....