99 tahoe problem... dont know what it could be..

Ive been going through some issues with my 99, 350v8 4x4 tahoe .. its not getting the pick up it should. Fuel pressure is good, both converters changed.. plugs cap wires changed..... recently my oil guage has been staying around 20 when idleing but 40 while driving ... but i think thats normal ...

when i accelerate and it switches gears it feels like it just drops it in to the next gears hard ??? if i stomp it from dead stop it doesnt gradually build speed fast ... it builds up and finally releases a big blast, when this happens you can hear a little noise chattering under the car .. ive been told that it is just a heat plate.. because it doesnt happen unless i stomp it ... could this really be a problem .. also when i turn then AC on its very sluggish .. and sometimes its just sluggish all together .. soo could anyone narrow this down a little ... anyone ever had these problems ....

i dont know if the person before me changed the intake manifold gasket but could that be the problem ..

also is there a way that i could turn on my check egine light ... its never come on .. i think someone tampered with it ????

How many miles on it?
Last tune up?
Get the codes checked in the computer.
If any codes post back?
What was the fuel pressure running on the road?

130,000
2 months ago
no codes ever ?? my check engine light never comes on... ive changed at least five things on it .. but it never comes on .. ??
ive had the fuel pressure tested it runs on about 55 psi

i said that it needs to be 60 - 65 and they disagreed and said that its where it needs to be .. ??

Your fuel pressure is to low.
Find a good repair shop that knows what they are doing.
Sounds like someone punched out the check engine light.
Get it on a good scanner and read codes.
And work on that fuel pressure problem.
MT

ok heres another thing ... the fuel gauge is jumping around like crazy ... could that mean something ???

Only the gauge is bad.
But check fuel pressure.
If it needs a fuel pump you can kill 2 bird in one shot there.
MT

thanks man ill check again ...

tps...they go out about every 50,000 miles

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.