Major hesitation starting off

[bradterry]

I have a 2000 Silverado that I just bought a couple of weeks ago, and last week it started acting funny when I pull out. If I press the throttle a little or at least less than half way it does fine, but if I try to get on it the truck just barely moves. After I'm going down the road a little I can floor it and she does just fine, awesome really, what would cause this?

[rjgti]

tps

[bradterry]

I checked it and it seemed okay, but maybe, I'll check it again

[rjgti]

use an analog meter to check it or a scope

[bradterry]

It checked fine, what else

[CapitalTruck]

Does it act like it's about to conk out? I'm wondering if failing fuel pump. Sometimes they don't just quit, sometimes they start to lose volume. Does it do this with a full tank of gas? Just for haha's, try filling up.

[bradterry]

Yes it acts the same no matter how much gas is in it, I'm planning on changing the fuel pump anyway because the gas gauge is failing but I wanted to wait till the pump went out. But with 248,000 on the truck it may be the pump. Anything else you can think of?

[CapitalTruck]

That's all I can think of. You're sure it's downshifting right? Meaning (and it does sound this way) that you have isolated the problem to the engine, not a transmission that's failing to downshift.

All I can think of off hand is weak fuel pump.

[rjgti]

maf, and how did you check the tps?

[bradterry]

Yes it's shifting right and I have isolated it to something electrical, I used diagnostic software and a multi meter to check the TPS and MAF.

[rjgti]

so you say it is temp dependant, any pending codes. one or both knock sensor over torqued, temp sensor not within cold spec

[bradterry]

It was a dirty mass air flow sensor, thanks guys

[CapitalTruck]

I thought you said you already checked the MAF sensor?