2003 Chevrolet Trailblazer • 90,000 miles

Good morning,

I have a 2003 trailblazer and trying to figure out if I have a transmission issue or not. I have taken my vehicle to two shops and they have found nothing. I was wondering if you could guide me in the right direction with what might be wrong or what I can ask the mechanic to look for.

1) Lost about 2-4 mpg
2) When I am going about 50 mph on a slight incline with the throttle being steady:
the rpm's jump up and down until I step on the gas or let off
the car seems to bog down
3) When I have the cruise set or just footing the pedal going 70 mph'ish on an incline
The car bogs way down and then decides to shift down which then revs the engine way up.
This doesn't happen all time and the engine light does not go on. Could this be a transmission issue? Electrical? Etc.
September 18, 2012.

Symptoms don't indicate a transmission problem. You are losing performance that is affecting the mileage and it could be fuel, EGR or ignition related.

It could also be due to a dirty MAF. Have it cleaned and retest.

Sep 18, 2012.
Throttle body was cleaned, from what I get trailblazers dont have egr

Sep 18, 2012.
Not throttle body, that does not affect the performance, only idling. The MAF and TPS would affect the performance.

Sep 18, 2012.