My 03 monte carlo is very sluggish. The engine

accelerating I assume?

is your check engine light on?
possible causes are
cheap gas - egr valve - timing too high - carbon build up in cylinders

I'd suspect a sticking injector--car should have set the check engine light. Read the code(s) to progress further. If the coil pack were a problem, it would not be likely to fix itself. If the codes indicate an injector problem, try an injector cleaner in the fuel--worst case, replace the bad injector. The codes should indicate which cylinder to change the injector.

The "won't rev" part sounds like a preventative so you won't destroy the engine from cold start-up. The sluggish part sounds like bad fuel or spark plugs. Where do you buy your fuel and what octane is it? and have you Changed your plugs?

If you are driving the car and it wont start after driving awhile. Do a wiggle on the CKP (crank position sensor) this sensor is located at the front main engine pulley, I am seeing a lot of loose male to female connection shut car off.

possible mass air flow senser

Tumblers are going bad. Get a locksmith or dealer to replace.

YOUR TRANSMISSION COULD BE SLIPPING.CHECK TRANSMISSION FLUID EGR VALVE NOT WORKING .A STOPPED UP FUEL FILTER.BAD PLUG WIRES - PLUGS -COILS- WILL EFFECT POWER.

starter is bad

The rev limiter won't allow it to rev above 4000 in park. Will it go above 4000 on the road. Does it miss at ldle or under a load.