Trans acting up ??? Need some insite

[Gun50]

Hello All this is my first post....Need some help.

I'm sure this topic has been ridden into the dirt........???

Here's the deal..2000 Tahoe Ltd. Edt. L460 92k miles.(owned since new)
Having already replaced both front interior door handles, both front door locking solenoids 2x, left barn door latch 2x's, 3 sets of brakes, front rotors 1x, a vacum servo on trans to release it from park(at 87k miles), oh at 27k miles the brake pedal pad broke off it's weld( dealer didn't want to replace it under warranty until I went balistic and threatened to contact GM).

Now the trans wants to stay in 1st if I jump on it and keep it floored, sometimes it bogs won't accelerate but will stay at 4k rpm and 20 mph until I just lift off the pedal, then it shifts. I'd reprogramed ecu (hypertech)to shift harder and to run on 87 octane, fuel filter just changed. Never had a problem. The trans works normally under regular throttle, it just jacks around when floored and held there ?? I just reprogramed the ecu back to stock and it's seems worse.
I do tow a small trailer for my track bikes approx 1300 lbs loaded. Last Sunday I was towing a 2500 lb. trailer in high heat 105 degrees and I think it started after that?
Possible speed sensor on trans? It feels as if the trans line pressure is to high and won't let it shift. This has just started to occur......I'm stumped, and hope to do the repair myself.

I'm a fanatic about mainteance ! Oil & filter change every 3k and trans every 12k miles.
__________________

 

[wicked2000]

Check your cats. I had a similar problem on a gm car. I thought it was the tranny because it wouldnt shift. I was testing out at night when I noticed the cat was glowing red, once I replaced it problem solved.

 

[Gun50]

Well they said it was the Cats.

Spent $520.00...2 new magna flow cats....still the same....

Spent $125.00 to diagnose it.....
Now they say it's dirty injectors.
Told me to run a bottle techtron and and a tank of Chevron 91 octane........80 miles so far no change.......

Today put the trans i 1st/low....got on it and it shifted into 2 nd.....????
Is it suposed to shift.......???
tried it 4 times shifred each time..........
On the 5th and 6th try it stayed in low/1st.......I'm baffled and broke ????
Anyone have a clue.....point me in the right direction !!!!

 

[steamroller]

Now the trans wants to stay in 1st if I jump on it and keep it floored, sometimes it bogs won't accelerate but will stay at 4k rpm and 20 mph until I just lift off the pedal, then it shifts.
__________________

Sounds like a fuel delivery problem, get a fuel pressure gauge with a long enough hose on it to lay on the windshield, hook it up to the test port on the fuel rail, go for a drive and see what it reads when this occurs. It should be at or above 60 psi at WOT. If it's low the fuel pump may be getting weak. 5.7 Vortecs are picky about fuel pressure


Another thing to check is the distributor gear, I've read of guys having all kinds of weird issues when they get worn