I have an 02 cavalier with the ecotec motor. I just replaced the motor with an 03 sunfire ecotec. Check engine light is on and says misfire and bank 1 rich. The car starts but runs rough and pops, but after a mile down the road it smooths out and runs good. This happens when motor is cold or warmed up. I swapped the icm and coils, swapped the fuel rail and injectors, coolant temp sensor, new plugs. Fuel pres. is at 58. Compression is 150 on all cylinders. Any ideas?