Hello,

My wagon has a bit of an issue lately that I'm struggling to diagnose. I recently replaced the engine wiring harness with a newer, used, volvo harness and cleaned up the fuses. Before the replacement, the idle was irratic, sometimes right at 900, sometimes up at 1200.

Now, the car starts and idles always at 500 rpms. This persists during the warm-up period of the engine. Then after a few minutes of driving, if the engine was cold, or 30-seconds or so, if the engine had already been running, it feels like the gas supply cuts dramatically for a second or two. The engine does not die, but it will not accelerate. (Kinda scary pulling out of an intersection!) After I let off the gas for a second or two, the car will resume fuel delivery, and everything will be fine. Thereafter the car idles nicely at 900-1000 rpms. This happens every time.

Any thoughts? Did I bum up one of the connections with the updated wiring harness? Could it be the TPS or ECU or the idle control valve? Dis the newer model 240 wiring harnesses have some differences with regards to fuel delivery during engine warmup?

Appreciate any help!!!

Regards,
Glenn