I have an 88 S4 N/A. 5 speed. I have to unplug the pressure sensor or she dies at anything below 3000 rpm then she runs smooth. I can press on the accelerator (sitting still) and let off and she sort of backfires once or twice but continues to idle smooth thereafter. I have replaced most all the vacuum lines, new fuel pump getting 12v at pump and new fuel filter with the pressure right at spec. When driving not much power but runs smooth. Ideas?