2004 Malibu Maxx just replaced the alternator and the serpentine belt. Car truns over and runs but there is no acceleration when pushing the gas pedal down

SOURCE: serpentine belt replacement on 2001 impala

I bought a new belt and it had a series of diagrams for different engines on the cardboard packaging (ie GM 3.8L). I needed it for my '01 Impala.

SOURCE: Replace Dash light bulbs on 2004 Malibu Maxx

you need to take the hole dash out and on the back of the speed dash there are little bulbs take them out then replace them

SOURCE: Stuck CD in the multi CD player of 2004 Chevy Malibu Maxx

The only thing that is left for you to do is to remove the stereo and then disassemble it and remove it yourself. A little daunting but needs to be done. Sounds like it went in wrong and then became jammed

SOURCE: Hatch won't open on 2004 Malibu Maxx

Try pushing the trunk release and turning the key in the lock at the same time.
It sounds like the electric lock has not released for what ever reason.
You should hear the trunk release relay when you push the remote.

John

SOURCE: How do you change the serpentine belt chevy malibu 200

Well you don't have to remove the tensioner. If you look at it, you'll see a 3/8 square hole in the arm of the tensioner. Put a ratchet wrench, or breaker bar in the hole, and you can move the tensioner, it is only spring loaded. The diagram for how the belt laces in should be on the radiator core support. Lace it for the majority around, move the tensioner, and once you have the belt in line, release the tension on the tensioner arm.