engine has a miss, only when car is going up hill on 1998 Pontiac Bonneville

I've put plugs,wires, new coil pack, fuel pump and filter, gas tank completely flushed, gas cap, Car went in for service, ran good and still does, until it goes up hill. drove car about a week, after service, check engine light came on, and the miss started.

by in Madison, IN on December 12, 2010
Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
2 answers 1 comment
ANSWER by , December 12, 2010
what was the code for the light?? Roy
COMMENT by , December 23, 2010
oxygen sensor
ANSWER by , December 25, 2010
Ihave same problem except i have not replaced fuel pump ,it does not occurr all the time