So after installing the 746 injectors on my 1990 xj, and after warming up and going on a drive, everything sounds/drives excellent. Then when I stop, put it in park, the idle varies from low to high constantly. If I put it back in any other gear, even neutral, the idle problem goes away. I've checked for vacuum leaks, and injector seating. This problem was nonexistent with the stock injectors. I'm not sure where to start. I didn't adjust anything else during the swap. Any ideas. my CPS, TPS, ECU, throttle body and IAC are all clean/no more than 6 mo old. It runs like a champ. Any ideas?

 

Check the throttle body to MAP hose/tube for cracks, pinches etc.