94 z71 trans prob

i have a 94 z71 it had trans built 6 months ago and has been doing fine and all of the sudden it will not shift in od stays in 3rd gear. while it is in 3rd and try to speed up and engine speed gets to about 2500rpm it shifts down to second and stays there until you let off the gas any thoughts

Could be that the throtle valve has been adjusted incorrectly, or you have valves in the valve body sticking. I would take it back to the place that rebuilt it and make them fix it.

Could be that the throtle valve has been adjusted incorrectly, or you have valves in the valve body sticking. I would take it back to the place that rebuilt it and make them fix it.
I just bought the truck about 2 weeks ago and the guy had the trans rebuilt 6 months ago i asked him if he had a warranty on it and he said no i done some trouble shooting of my own and found that pcv valve line was stopped completly up due to line was broke and duct taped together i repaired that but did not fix it ive noticed reading in repair manual it talks about the tv cable adjustment but this truck is not equiped with that i was thinking that the problem is somthing to do with what ever controls the downshifting cause it is shifting fine until you get in 3rd and it pulls out fine in 3rd unless you try to accelerate then it shifts to second and want shift out till you let off the gas

I'd put a new fuel filter in it first and if that don't fix it, look for intake leaks and check the voltage range on the throttle position sensor

Is your SES light on? your truck does not have a TV cable as you have found out. You have two shift solenoids 1-2 & 2-3 and a 3-2 down shift solenoid a EPC and TCC solenoid. If you have 2nd your band is ok and if you have 3rd your 3/4 clutch pack should be ok. It takes the Band and the 3/4 clutch pack to get 4th. So I think you have a electrical issue. Any other issues with the truck? I think 93-94s have issues with the PCM (computer) failing. the PCM is behind the glove box.

i went and bought a autoxray to see if any codes were present and there are no codes will that autoxray read trans codes without the upgrade also i got under the truck and found that the case harness had trans fluid coming out and the connector will fall in the trans while trying to plug it back in after doing this i went and drove it again and noticed it will try to shift in overdrive at low rpms and act like it is hunting it go back and fourth between 3rd and 4th i also bought a tech manual for the trans and it said if you disconnect that case harness it will log codes i done this just to see if it would and still no codes thats why i was waondering if that scanner would read trans codes