Transmisson problems?

Hey guys new to the forum here I got a 99 Silverado z71 with 266k on her. Well my problems started yesterday morning going to work when I got to work I tried backing into my parking spot I got to put it in reverse and to start backing up and the truck acted like it was in neutral. So without thinking I shut the truck off turned it back on and tried again and it worked like nothing ever happened. So I thought nothing of it sat there with the truck running since I'm there early I figured I had enough time to go get a bite to eat so I put it in drive And go to pull out and the truck was acting real sluggish taking off in 1st almost like it was slipping again restarted the truck and the problem was gone get back to work parked it. This is only the beginning of my problems ( I guess the saying is true " when it rains it pours") lol well later that night on my way home on the highway I noticed the truck was shuttering periodically and the rpms were at around 2000 going 65. When the real problem started was when i came to a stop light and go to take off it was really sluggish and slipping pretty bad so I pulled into a gas station stop and restarted the truck and it temporarily fixed the problem tell I was five miles from my house this time it started slipping really bad ( I almost thought I was going to push her the rest of the way home!)I was able to limp it home thankfully I also noticed it skipped 2nd and went into 3rd. What I'm stumped on is why everytime I shut it off and restart it, it acts like nothing happens tell later down the road. Could it be a computer problem or is the transmission done for? What you guys think? And thanks in advance!
- Merica

you may need a re-build. these came with dexronIII transmission fluid . the fluid is defective and NO LONGER an approved GM fluid ![2006]

I would have a repair shop do the pressure checks . that should indicate if its in need of tranny work.

also make very sure they put dexronVI in it NOT dexronIII..............VI does cost more so they may try to use the cheapo fluid so they can pocket a few extra bucks and down the road create more work.

most good repair shops include a 1 year warranty and a re-check after the repair work to ensure all is good.

Welcome to AF

Did you notice if the tranny shift indicator lights were lit when the issues were happening? Reason for asking is that the ign sw has 5 contacts, one of which is dedicated to the trans fuse.

Yeah I got a transmission shop right down the road I plan on taking it to get it checked out. I just bought the truck so I've got no idea when the last time they serviced the transmission figures why they were trying to get rid of it lol. But to answer your question bout my shift indicator, I forgot to mention that it dosent tell me what gear I'm in 99.9% of the time that's another reason why I was thinking that it might be a computer issue.

Yeah I got a transmission shop right down the road I plan on taking it to get it checked out. I just bought the truck so I've got no idea when the last time they serviced the transmission figures why they were trying to get rid of it lol. But to answer your question bout my shift indicator, I forgot to mention that it dosent tell me what gear I'm in 99.9% of the time that's another reason why I was thinking that it might be a computer issue.

on the shift indicator you mean it does not light up ? if so that would be the dash display panel. odometer indicators are also a problem as well. circuit board most times has bad weak solder joints..

on the shift engagement like the reverse could be the switch on the side of transmission and the bracket at the side of transmission, some repair techs/owners will bend that bracket to get the tranny pan off. that does mess up the shift cable operation . then it also could be the shift cable as well..

post back what they found . good luck . 2007-present GM truck will never get to your mileage .

No the shift indicator lights up fine it's just when I shift it to a any of the gears it won't cycle through and show me what gear I'm in, also when I'm in neutral my reverse lights come on but when in reverse they don't. I know that the PNP switch and the reverse switch are intergradated in one ( correct me if I'm wrong ). So maybe a faulty PNP switch? Anyways here's where it gets really concerning! I finally got time off of work, I work in the oilfield so that's rare, I drove the truck around the block to try and replicate the symptoms and it did and also trying to hear the truck up to operating temp so I can check the fluid and it's way over full!!!! And also noticed it was a dark red color with a hint of black in it, so I read online somewhere I can suck out some tranny fluid through its dipstick, but I'm wondering if I should just go ahead and replace the tranny fluid and feel it up to the right amount. What you guys think?