4l60e problem or TPS, need help!

[chevyman70]

I have a 2003 5.3l with 4l60e on my c10. I drove it today and I noticed the transmission is downshifting hard when coming to a stop. I could feel 3-2, 2-1 downshift hard. Also, the 1-2 is delayed. The transmission was recently rebuilt, oil still clean and does not smell burnt. I check the tps sensor to see if it reads smoothly when I press the gas pedal, and it does, I think. with the engine off, the tps reads 18% and it moves to 99.6%, then back to 22% when I let go of the gas pedal for a few seconds, then it will return to 18%. When on, it idles around 3.5 to 5%, when driving I noticed it would return to 5%, but then fluctuates between 8-12% when I let go of the gas pedal and that is when it starts to downshift, or upshift 1-2 hard. I also notice that it seems like when the throttle cable or rod gets stuck on a carb when coming to a stop. It wants to continue even though I am not pressing on the pedal (drive by wire). So before I take it back to the tranny shop, I would appreciate it if someone can provide guidance. Thank you in advance.

[BR3W CITY]

DBW cars usually get b!tchy about TPS failures, so I'd think you'd pop a code pretty quick, and might even get a total-limp if the DBW doesn't want to work.

When your in neutral , how does the pedal "feel" in the rev range? Does the car stumble etc?

You may also have the lockup-issue thats common on cam-swapped dbw cars. The misfire counter needs to be offset/modified (value) to ignore false misfire caused by out of phase cam sensors on low-lsa. Lockup problems can also be caused by bad or poorly setup brake switches.

The bouncy tps data is probably just confusing more than helping, lets try to narrow down a couple factors and work from there.

[solidaxel]

Check and make sure the o2 wires did not get pinched between the engine and transmission, when you installed the transmission

[chevyman70]

funny thing you mentioned O2 sensors. While I was looking at the tps sensor, I noticed the fuel system going from close to open back to close. At time the sensors were not isolating from .100 to .900 like they normally do. I drove it when it was doing this to see if it affected the shifting points, and it drove horribly. It finally set the MIL lamp on P0135. I reset it and the O2s started reading normally, and again drove it to see how it drove, and the shifting improved. I have Bosch O2s and I know they gave me problems on another vehicle I had. So I am going to change them out with Denso's to see if it improves.