2004 Oldsmobile Alero

Engine Performance problem
2004 Oldsmobile Alero 6 cyl Front Wheel Drive Automatic

hi guys I hope you can help me. My alero hesitates
and kind of surges while traveling on the highway. She starts up fine and runs good but after traveling a few miles on the hwy the car rpm drops (about 3-400 rpm) and back up again. This continues until I pull over off the road. While in park I raise the rpm and notice the surging continues at 1200-2100 rpm. As I start to move again it runs like that even at slower speed. I tookthe car to the dealership (by the way no check engine light/service engine soon light comes on) and they checked for codes (none found) and ran a diagnostics with no problems. The y changed fuel filter and " flushed" the injectors. Later that day it sarted happening again. I changed all plugs and wires and no change. I just replaced fuel pressure regulator and still no change. I dont want to take it back to dealership because no codes are showing and their way of troubleshooting is to replace items instead of trying to properly t/s and repair. This will become very expensive and I cant afford that. Please help! Thanks!
October 11, 2008.

This will be a process of elimination. You will need a manual fuel pressure gauge to be able to watch and verify fuel prssure is staying strong the entire time. Could possibly be exhaust related too, try loosening the exhaust syetm before the cat converter and driving it to see if it does the same thing

Oct 15, 2008.
I have been having a similar problem did you ever find out the problem?

Jun 3, 2009.