I have an 01' Silverado with the 5.3L and I replaced the fuel pump and filter a couple of months ago, but now while cruising about 40-50 mph and let off the gas the Rpms bounce up and down. Now keep in mind i did run it low on fuel a couple of weeks ago, but i dont think it could be the fuel pump again. My SES light also came on this morn. and when setting in gear idling it runs from 4 to 700 rpms. Any ideas or suggestions would be helpful thanks.

 

If you have an SES light, then the computer is throwning a code to tell you where the problem is. Go to an auto parts store, Autozone, Oreilly's, Advance, etc. and get them to read the codes for you. Knowing the codes, someone here might be able to help you.

 

i second RonH's opinion