Automotive Forums

I have an '04 Chevy Avalanche Z66 5.3L with the 4L60E with 44k miles on it. At 27k the tranny was rebuilt at the dealer under warranty due to a leaking front pump seal. after rebuild tranny was slow shifting from reverse to drive and vice versa, dealer said that was normal, all line pressures and specs were normal according to diagnostic tool. After complaining enough they looked at it again and found a bushing had slipped out of place. tranny seems to operate normally during normal driving. When needing more engine braking for decending mountain passes (denver area) and manually downshifting rpm's drop to 900-1100 rpm's until I put it back into Drive. Feels like it went into neutral. Also the tow/haul feature does not work. didn't find all this out until the work was out of warranty. Vehicle was getting 16.2-16.8 mpg before rebuild and now is getting 12.8-13.4 mpg (miles driven/gallons filled) immediatelly after rebuild. tires were replaced from goodyear wrangler HP to Wrangler A/T w/ Silent Armor at same time as rebuild. Told dealer of this drop in milage, they blame the 20% decrease on the tires. Could any of this be a computer problem or a poor rebuild.