99 Silverado 6.0 , Seems To Surge at low rpm when in overdrive???

[SilveradoGuy82]

Hey guys,

I have a 99 Silverado 6.0 4L80E , and from time to time when im at lower speeds (20-40MPH) just cruising in overdrive at low RPM if i come to an incline sometimes it seems to surge and or almost like a miss fire or something along these lines, but as soon as you take out of overdrive or use a bit of pedal and let it down shift it's fine, it doesn't do it all the time it just happens mabye once every few days, but man is that anoying, it jolts you in the seat and im sure it cant be good for the truck... I'm wondering what this could be caused by and if anyone has run across this problem...
I'm stumped at this point... mabye a sensor or soemthig??
any suggestions would be appreciated :-)

Thanks Guys...

- Jimmy

[maxwedge]

Welcome to AF. This can be caused by a intermittent misfire under load ( o/d), lean mixture caused by marginal fuel pressure. State of tune , quality of plugs and wires also. Fuel pump pressure should be checked, fuel filter also.

[SilveradoGuy82]

Thanks for the help, I had figured it was some sort of misfire, i just put a K&N filter kit in it , and clean out the MAF and throttle body, time for new plugs and wires as well then :-)
i have about 185,000KM on the odometer and was wondering if the fuel pumps run pretty loud on these trucks, mine hums along quite good but has done so since I bought the truck used with around 100,000KM on it, but this missfire problem didn't start til about 4 months ago....

[maxwedge]

I'd test the fp just be sure, 60-65.

[SilveradoGuy82]

What would be the best way to test the fp, should I take off a fuel line from one of the fuel rails? and check it there to make sure the pressure is what it is supposed to be right at the injectors?
hrm, i hope its not a plugged injector or something ...

[maxwedge]

Get a fp gage on the test port on the fuel rail, looks like a tire valve.