2000 Chevy Silverado 1500 problem?

Question

Trying to maintain speed at 50mph or 70mph is impossible. I keep pressing on the gas pedal but my speed starts to slow. I have to press hard on the pedal to get it into passing gear. Then it speeds up and begins to slow again. It doesn't happen around 60mph, just around 50 and around 70. When cruise control is on, it shifts all over the place, frequently in passing gear, like it is confused. Put fuel injector cleaner in and punched it a few times on the expressway, but it didn't seem to improve anything. Tranny fluid is fine. Anyone know what may be going on?

Answer 1

it sounds like the fuel pump regulator. also you might want to change the gas filter.

Answer 2

You should take the truck to a driveability professional  and let him look at the data stream and the rest of the vehicle. It may be a fuel pressure problem but who wants to guess? You will probably end up saving money in the long run.