I have recently had a remanufactured motor put in my 90na due to a blown apex seal. Ever since I got it back from the shop it stutters at about 3000rpm when i am cruising, sometimes it will also do it at higher rpms. I have the sixports opened via the airpump with a garden hose ball valve that sets what rpm they open at. The car was virtually undriveable at one point. I don't know why but i decided to close the garden hose valve that opens the sixports. This seemed to help immensley, the car drove fine for a day but was noticeably down on power do to the non opening sixports. Later on in the week it started to stutter again at higher rpm even with the sixports closed. It still stutters a little bit but runs smooth at sustained lower rpm. Could this problem have something to do with the egr valve or the air pump, I need help because I can't run my nitrous with the sixports closed because it creates nitrous backfires.

 

The 5th/6th ports are normally operated by the airpump without the garden hose set up on the series 5 cars... was something changed that you had to use the garden hose setup???

 

that was all I could find at the hardware store that would fit the hose that came of the air pump. I think that the six ports are opening then closing right back up causing my car to load up. I went to K-mart tonight and bought some wire and I am going to wire them open and see what happens when I do that.