2004 Z71 5.3

[Devin Daniels]

This is really hard to explain,  but I have a 2004 z71 with the 5.3 , 4l60e, the truck runs good not the best but good when you first start it up , but let's say you hit a really long red light or get stuck in McDonalds drive through,  and your sitting and idling for more then 5 - 8 minutes,  the truck develops these awkward shift point , and when will barely climb up to 65mph , and at say you want to pass someone because their doing 50 in a 65 you give it enough throttle it barely kicks into the passing gear and will hold 2500-3000 and start studdering and popping out the exhaust , same goes for trying to climb a hill you'll be going 65 at the star of the hill and 40 by the top

 

The transmission isn't freshly built but is about 1 and 1/2 years old rebuilt, my mind is telling me maybe it's over heating even though its sitting? Is it starving for fluid? I really dont know, 

 

Any tips or tricks to try would be fantastic. Thanks .

 

 

(Edit)- truck will reset to normal after it sits long enough with key off while getting gas 

[davester]

What is the transmission fluid temp?  Have you gone through the fairly involved process to check that the fluid level is correct?

[rjgti]

and codes

[tlaw91]

Sounds like a failing MAF or bad intake gaskets. Would need an actual diagnostic though.


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[riverbanks]

Popping out the exhaust,to me,sounds like a cold motor,too much fuel,excess being burnt in exhaust,bad thermostat?faulty cts?motor is laboring,causing odd shifting