Acceleration problems

Based on your question and the way you've worded it, it sounds like your transmission is slipping. Check the transmission fluid. If the RPM's increase and the vehicle speed does NOT, the transmission is slipping. That's where I'd start.

I checked the transmission fluid and it seems fine and doesn't smell used. Would you recommed still changing the fluid and filter?

Not yet. If the level is ok and it isn't burned looking or smelling, then that may not be the problem.

Moving on.... Is the 'Check Engine" light or "Service Engine Soon" light on? If so, we need to see what the codes are. Look for maybe a Throttle Position Sensor code. If there's an "OPEN" spot in the TPS, the PCM (computer) doesn't know exactly what the throttle position is and therefore doesn't know what to do with the injectors. It could either starve the engine for fuel or inject too much. Remember, this is just another possibility. I keep re-reading your post and my mind keeps going back to the transmission, though. It's pretty 'cut and dry'... If the RPM's go up but the vehicle doesn't speed up, the power is being lost somewhere. Don't rule out the tranny. Let's try this. Re-post and describe, in as much detail as you can, exactly what's happening and when it happens. Be very specific. This could be a fuel injection problem, and ignition problem, or, like I said, a transmission problem. I'll be waiting for your reply. I'm going to do my very best to help ya...

Recently my monte carlo has lost power when trying to accelerate or when on cruise and going up long grades on the interstate. The car slows down and will kick into lower gear to 3000 rpm but doesn't speed up and then the service engine light comes on. Also, gas mileage is getting worse. Used to get 28 to 32 easy now down to 24mpg.

You need to see what code is setting to help aid in determining problem. At the moment given the description I would begin inspecting the catalytic convertor for damage.

Just the other day I started having problems with my Monte Carlo SS. I was passing someone, so i was accelerating pretty hard. At first it was fine, then it pretty much stopped accelerating all together and i was just reving the engine. Now when I try to accelerate, my car won't switch gears until i let off of the accelerator. I'm also getting a little shake in the front end now around 60 MPH that i didn't have before. Please Help!!!

i would start by replacing or checking fuel filter for blockage. low fuel volume will cause high revving without shifting. also if the check engine light is on get the computer scanned for trouble codes and get back to us. auto zone does it for free

I have replaced the fuel filter, and i've had the codes checked. They said something about fuel pressure and vacuum leaks. does that make sense?

i would have the fuel pressure checked. low fuel pressure will give false codes like map sensor high vacuum problem and also it will give lean codes. most likely its the pump but if you have the fuel pressure checked you will know for sure

so it wouldn't be a transmission problem?

i doubt transmission trouble. check fuel pressure