Did a rear main on a 240 Dl, The car was running perfect no codes till I worked on it. Right after reinstalling the trans the car wont idle and barely started. thought it was a fuel related problem because the car was on empty and was jacked up one end then the other, maybe the fuel pump clogged. replaced filter with a WIX and blew back into the feedline into the secondary pump hoping to dislodge any slit or crape in the tank sock. wasnt the problem. I installed the fywheel wrong and had to pull the trans again. Fully baptized in the religion of Volvos. Second time the car starts right up but is running rich. No codes drove 40 miles no leaks = Happy. Next day, codes 232 and 113 pop with idling. Pull all plugs, all are carboned up. cleaned and reinstalled no help. Clean AMM, no help, New FPR, no help. checked O2 sensor, fluctuates at idle good. Sensor test with OB1 is good... Good cap,rotor, wires, plugs..Changed oil .Whats next? check the fuel check valve of the main tank? I have a new sensor ordered anyway. Car runs great down the road. no black smoke, doesnt die at stop signs. Just throws the cell and idles rich and gets bad gas mileage.