Well I THINK it finally happened to me. I was going down a steep decline from a parking structure as I manually placed the truck in 1st gear and road all the way down with it. Once I dot on the street I placed the truck into drive and that is when my tale of woe begins. It would not shift out of first gear. I pulled to the side, checked the oil level it was fine. I shifted the tree up and down a few times but to no avail. I had to drive side streets home in first gear keeping the rpms below 3000 at 28 mph. But here is a few odd points.
6 blocks from my house I just decided to floor it for the hell of it and lo and behold it started to work....It shifted through the gears.So is the tranny shot or is there something else.
Now another thing, I just finished putting in a new water pump,hoses, (even the bypass) and the thermostat. It was just blowing ok temp and in the past whenevr I would apply the pedal I would get no air flow till I let the pedal back for cruising. The blower didn't stop just the airflow.
But now that the transmission went on the way home the airflow is constant no matter pedal position and its blowing real hot. I actually turned the heater off(first time ever). So I don't know if that is in any way possibly related due to vacuum or whatever.
If my trans is shot I want to rebuild it myself so any tips would greatly be appreciated. Did I mention this is also my daily driver so please help a needy man here.
Thanks alot guys

 

Have you changed the tranny fulid/fliter stopped up filter will cause alot of problems with shifting also with tranny running hot. filters are easy as hell to change, also consider doing a tranny flush once in awhile to keep it flowing free of metal shavings.

As far as your vacume goes mine does the same thing, if im climbing a hill the vents will shift by them selfs to defrost, then once i let off the gas it will shift back to the pannel vents, iv just learnd to deal with it in the winter because as long as it's blowing heat im happy and i usually have it on defrost 90% of the time anyways.

just a thought.

P.S

if i remember correctly i think some transmissions are vacume controlled, just like some GMC's are electronic. im not a transmission man other than just changing parts.

 

does your 96 have a vacuum line to the transmission? my old chevy does, and when its disconnected or leaking, it won't shift. i don't think yours does.... but maybe. other than that, all i know to do with transmissions is change the fluid and filter.

your air vents are also vacuum controlled, and your problem is bad check valve(s) in the engine compartment, passenger side, between manifold and firewall. do a search on "wild vents" for some pictures and a million posts.

 

i had tranny problems of the same, thought it was over for me. dropped the pan, clean the magnet, changed the filter added fluid and works great now. my filter was clogged is all it was. i wouldnt think twice about doing that first. you may be lucky like i was.

 

Change your fluid and filter, but by all means....and I cant stress this enough....CHECK THE THROTTLE VALVE CABLE!!. It sounds like you need to lengthen it.