I have a 1996 Chevy Lumina with a 3.1. I recently dropped a used engine in it from a 1995 lumina 3.1 that ran fine, the 95 had body damage. It ran fine

for 50 miles and then started to chug bad when idleing and was gutless when I would try and go forward or backwards. I would shift into 1st and play with

the throttle untill it would eventually kick in and take of fine. It runs fine at high RPM's. I read the computer codes in my shop class at school and it said

that the mass airflow sensor was bad. I replaced the MAFS and same problem presisted, also replaced oxygen sensor, and the engine has new wires and

plugs that are gapped correctly. There was also gas backed up into the air intake and the Oxygen sensor had very bad carbon build up,which indicates

the engine was running very rich. I get very bad gas milage also.


Can anyone help me and what my problem may be???