What in the ?? is going on? Had drivability problems. Replaced o2 sensor, ECU, ECT,FPR. The ECU was the last installed and solved the problem. BUT (even before ECU swap)the car starting running rich. Related to replaced parts or not? Tried replacing AMM. Made things worse. Finally gave up and took the car to a Volvo mechanic - I just wanted a diagnosis. Charged me $220 to tell me I had a bad AMM(new) AND bad (shorted)O2 sensor(new). Also cat. converter was getting clogged. They put the old AMM back in and disconnected the O2 sensor. The car drove home fine (all of one mile). I changed the oil, replaced the converter, replaced the O2 sensor(Walker 3-wire from FCPGroton) and reconnected the o2 sensor in the engine. Drove it around the block in the dark last nite, seemed OK. Now the wife calls and says the exhaust is spewing smoke. HELP@!!