RPM surges about 500; worsened progressively. After a 1 hour wait, problem appeared to disappear.

Miles? Have you replaced ignition coils recently? Pretty good chance that they could be going bad. I would start by swapping all 8 coils and plugs and probably changing the valve cover gasket as well as those are known to go bad in the 2000-2003 LS

fuel issue possibly MAP sensor or tps sensor? any check engine light?? transmission not shifting??

need to clean the screen on the IAC valve.

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I would check the MAP sensor first, and then the Idle air Control valve. If those check out it might be a vacuum issue. The EGR Valve has a line on it that is very good at leaking and can cause a rough idle.

I'am not sure but sounds like an automatic choke problem

Hi

It does look like you have a 3 speed C6, if the PRND21 description is correct. If you do have overdrive, the "D" will be printed in a white oval.

Sounds like it is OK. My Mustang has a 351C with a C6 trans, and 3000 rpm is about right at 70mph.

The defining factor on the rpm will be the Differential gears, which in a truck, might very well be taller gears instead of highway gears, as the taller gears provide more power output at the axles than the highway gears do.

Example:
if you had 3.0 to 1 gears (Highway), that means that the driveshaft will turn 3 times for every complete revolution of the rear wheels(Axle)

If you had 4.0 to 1 gears, then the driveshaft would turn 4 times for every revolution if the axle. Lots of torque for pulling stumps, but on the highway. the engine will have to turn more rpm's to maintain 70 mph vs a 3 to 1.

with the 3 to 1, you will turn less rpm's on the highway, but will have less available low speed power (Torque) at the wheels.

Sounds like the truck is doing fine.

It is probably the mass air flow sensor, you can try cleaning the small wire inside it (windex works the best) but chances are it will fault again soon after. replacing it is your best option.

Pin point the dead hole and check that injector.

You should have another gear "5th" at 70mph your tacho should read about 2500 rpm.
Make sure you don't need to depress something or push the gear stick against a spring to select 5th.
Is there a gear layout on top of the gearstick knob, do you have 5th gear on there?
The highest gear ratio is a little over 1 to 1 so at 70 mph you would expect 3500 rpm, but, it is a little over 1 to 1 so it will be closer to 2500rpm.