Over 3000 rpm the needle goes back down slowly but after 3000rpm is goes down normal. Stock ecu,injectors,stock turbo and it looks like it running rich since the rear bumper on the exhaust is black. Any suggestion what might happen?

 

What do you think cause the rpm from going by down?

 

are you talking about free revs or in gear?

 

How about a little background on the problem?

Did it just happen out of the blue or were you working on another problem and now this started?