Well I have a 2000 silverado with a 4.3 that has served my needs perfectly until now but I want to keep it just 0ne more year then I retire to buy a new one and travel Keep in mind I am the product of the 60's and weaned on small blocks etc etc in fact I own a 66 vette so this computer stuff is really a learning curve plus I'm 64 years old set in my ways
What is going on it when I start it it idles perfectly but when I put it in drive (when cold) it hesitates until I feather the gas then it runs ok UNTIL the engine warms up then when I accelerate it sputters bogs down ( little starves for fuel or air??) then when you floor it it bogs down with no power. Being that it has VERY high mileage (400K) I decided to replace every sensor on the top end ( TPS, EGR, you name it, I cleaned the throttle body, did the seafoam thing injecting it into the vacuum to blast the crap out, replaced the cats, replaced the 02 sensors, the coil, new plugs, new wires, new MAF but NOT the MAP ( maybe that's it?) checked fuel pump new filters, compression, timing ( which you cant adjust) distributor cap .rotor, magnetic pickup see if there was play in the bearings you name it but still zip It is starving for fuel or air I am looking at fuel.. I haven't checked the injectors yet but that is next ( they are only 2 years old) or the fuel regulator to see if there is a leak etc SO what do you think is going on?? I've gained a small education looking at those Utube fixerup videos but thats all I've gained which is a good thing?? So I need a direction to go to I'm not to savy on the names of these components so be kind as when I looked up how to check the air flow I had to look up what MAF stood for before I knew what the hell they were talking about but I am gaining an education and understand the "theory" If this was my vette it would be fixed yesterday
Thanks ahead of time ( I think)

 

400K miles? Wow! Goes to show how well these trucks are made and will last a very long time if well taken care of.

Okay, that aside, since it does have such miles on what I'm assuming is on the original engine since you didn't mention getting it replaced, did you do a compression check?

Also, are you getting any check engine light or codes?

 

Yes this is the original engine I did a compression test . all the "holes" were within 11-8 psi of each other what a surprise for an engine with 432639 miles on it now! This is what I have done so far
Replaced the following:
cats
all 02 sensors
TPS - cailbrated )
MAF
EGR
fuel filter
air filter
plugs,
D cap
Rotor
wires
magnetic pickup in Distributor
Fuel check ( 51 psi ) I suspect the Fuel pump may be the culprit
Replaced spider 2 years ago
vacuum leak (propane ) and a cigar smoke test ( not at the same time)
nothing found
Cleaned throttle body
injected sea foam into vacuum to clean carbon etc ( 2 cans ) not all at once though
I have a new distributor and was going to replace the old one thinking there is "play" in the bearings etc but looking at this how do you remove the old one as there doesn't seem to be enough "head room " above it to take it out!?? What brilliant engineer designed this? I don't think it's a timing issue otherwise I would see it when it runs and I rev it up without a load it purrs like a kitten then BUT put it in drive and that changes !!
Since I put all this new stuff in it it does run better than it did when this problem first reared it's ugly head but the bogging down thing has to go as I can't pull my boat out of the water due to no power!! when it warms up Really appreciate your input
Yes I got a crap load when this first started now I get a low air flow MAF when it starts to bog down and also one that says it is running lean bank 1 but not all the time If I don't press the issue with the bogging down ( feather the gas to get up to speed) nothing comes up