my 91 chevy s10 w/auto pops out of 4 high when i let off the gas but stays in when i accelerate. is this a serious prob? do i need to rebuild my t case?:(

Is your push button or lever activated????At leaste I would check the fluid and refill the t-case to see if it goes away if it persists I would rebuild the t-case. I have never heard of Chevys having an issue like this.

i actually had a problem with my 87 k10 with the lever..it would pop out like his is now..i was low on fluid and also, the best way to stay in gear is pull the lever back, hold it and drive 50 feet and it will stay.

Sounds like an linkage issue as well.