Strange acceleration problem.

Maybe yall can shed some light on this also.
'99 Silverado 4x4, 5.3l, 3.73.
Problem: when driving at any speed with the cruise set at say 55 on level
ground it drives perfect. but lets say I start to go up a hill and it needs to downshift and accelerate to maintaine speed. Just befor it shifts and the rpms raise the motor starts acting like it wants to die. It goes to stippin and stuttering pretty bad UNTIL it finally shifts and the rpms come up. Very strange.
History: I've owned the truck for like 3-4 months and all I have done to it is total fluid and filter changes(all mobil 1 synthetic and wix filters) (minus radiator) I have changed one spark plug becuase all the rest looked to be in pretty good shape, only changed the one becuse when I was taking it out I cracked it. I know I need to do plugs, wires, cap rotor sometime but I was going to wait till spring when work picked up. I also JUST had the fuel pump replaced under warranty. Both myself and my mechanic friend thought that the fuel pump might be whats causing the problem I stated. But as of today it's still doing it. We have yet to check fuel pressure after the regulator and we don't know about injectors. I'm more suspecting it's electrical now.. any way I could put my finger on this a little better?
Thanks Adair
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Fuel filter?

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thinking about changing it anyway just in case.
Adair
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Bad pickup coil. Sounds like the problem I had. See if you can get it to do it from a full stop with a sudden part throttle under 1500rpm.
Cheers

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Ok I'll see if I can make it do it.. Haven't ever seen it do it under those conditions but will see.. Thanks! Adair
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Ok, Then there is a sensor on the crank or camshaft some where.
Sounds like a false trigger in either case.
Cheers

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Where is the TPS located and whats it look like? I'd like to at least check the connection and wiring there.
Adair
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I'm also gonna guess this has something to do with my hard shifting problem with in tow/haul mode.
Adair
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Two/haul will shift harder anyways, it's supposed to.
Doc

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but when I say it shifts hard.. I mean hard.. it jerks the whole truck.. i dunno maybe it's sposed to.
Adair
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wrote in message

TPS is located on the throttle body. It will be linked to the throttle plates.
Doc

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