So we done a tune up on my friends C1500 it has a 5.7 with a TBI. Just redone the distributor cap rotor button spark plugs wires air filter positive battery wire had the alternators bearings replaced new serpentine belt thermostat radiator cap. And it sounds great when revved but when your on the highway it runs good up until you need to pick up speed it just bogs down there is no overdrive at all it just slowly takes its time gaining speed. And if you try to go uphill it looses most of its power and slows down to 45 mph. We are looking into replacing fuel filter too. Any suggestions would be appreciated

 

So are you saying it won't down shift to a lower gear? And did this problem exist prior to the work you did?

 

It had that issue long before. The best way I can explain it is if you're driving uphill and you start slow down with your suburban you press the gas and you accelerate nicely because it kicks into overdrive. Sadly it doesn't do that on his truck. you press the gas the RPM's go up and acts like its going to go into overdrive and then it doesn't

 

Sounds like a trans problem (not downshifting), not the engine. Any codes pulled yet?

 

Haven't been able to yet this year does not have and OBD port on it. And the factory radio display is damaged so we must replace before we can pull them of the display

 

Hopefully not that but if it is o well. Just frustrating not thaving a passing gear on the highway

 

i believe my 93 sub has a port below the steering wheel under my left knee

 

OK will inspect