90 Lumina Euor 3.1L Passing Gear Problems

Automatic Transaxle

The car shifts ok. However, if you are in second or third gear and want accelerate as if to pass something or to really go, the car acts as if you shifted into neutral and engine revs up alot. If you release the accelerator and the engine rpms go back down, the car continues normally. You can increase speed moderately by pressing the accelerator and easing off, but if you really need it to buckle down to pass something or just speed up, the gear is just not there. If I went to pass a tractor trailer on a two lane highway, I would be in trouble.

What is going on?

Also, the speedometer is now 10-15 mph fast? What causes that? The vehicle speed sensor? Above problem been going on for several years, but speedometer just happened recently.

not sure about the gear thing. But as far as the speedo being off, have you put larger wheels on the car or is it stock? Different sized wheels would make a speedo be inaccurate.

no different wheels or tires. car did sit for a while, like 6 months - maybe something corroded?

if the trany fluid is low it will rev like it is in neutrel