'06 Aveo. a few weeks back, my son was driving it and it started to shift oddly.
He gets it towed to the house, we start digging in. Plenty of A/T fluid, idles fine. When running, it shifts "late" like in the 3,500-4,000 RPM scale. And when it shifts from 2nd to 3rd, 3rd seems to "shudder" almost like it's not sure it wants to be in 3rd.
scanned the engine, had some throttle position sensor errors, figured it was time to change out the throttle body. Throttle body switched out.. Idles better, still does not shift right.
Took some time to look at vacuum hoses. Found a couple of questionable hoses, replaced them. Small hoses, nothing much. took it out for a test. Seems to like 3rd gear better, but still shifts late.
had the transmission scanned by a friend who has a shop and offered to scan it. no transmission codes.
any thoughts? MAP sensor? PVC valve? Anything?