Help i have '99 blazer ZR2 4.3 with 180k on it. here's my problem I have a power surge at low cruising speeds right around 1500-2000 RPM jumps around 200 RPM don't notice at higher cruising speeds. Also, after getting gas every time as soon as you leave the gas station there is a loss of power once you put your foot in it to get going it clears up this only happens after getting gas. Now,I have done a tune up changed all the O2 sensors,fuel filter,new exhaust including the cat, had the injectors cleaned and a new coil (other one went bad). Now, I'm pretty good with cars and do the work myself but this one has me stumped.Also, after changing the O2's the chk engine light would come on I had GM check it and they said all were showing up as a code. I didn't put junk in they are Bosch O2's now the light will come on and go off sporatically. Right now the light is off and it is power surging. thanks for any help

 

Bosch o2's don't really agree with chevy's so much. I'm not sure why, but a lot of GM vehicles have weird problems with Bosch sensors. I'd start with replacing those with an AC Delco. I realize you spent a lot of money on them, but theres an issue there, Especially if your getting codes. Having o2 sensor problems can cause some funky problems, possibly even the one your describing.

If I were you, I'd start there. Of course you can post the codes, and then follow the diagnosis charts to verify the sensors are the problem if you like. That way you can save money from buying new sensors, just in case.

 

Thanks for the advice I will just go ahead and change them anyway. after all its only money