2002 Intrepid transmission problems 3.5

I let my son drive my 2002 intrepid for one day and he calls and said the RPMs were running high and he could only go about 35-40 MPH. I got in and drove it too and it did the same thing, feels like it is not going into the next gear..
Also in the Parked position, put from PARK to REVERSE it grind and than jumps hard into gear, same with putting into DRIVE from Neutrul.

my boy swears he was not beating on the car(not like i would don when i was 17) and he said he didnt hit anything.

ATF looks Ok, reddish, dont smell burnt, is at the correct level.

need help! dont have the $ to replace tranny

The 1998 and transmissions do not go out and hold up.They sit on the shelf at most wrecking yards.The 1998 and transmissions have speed sensor problems and that is it.Does the service engine light come on?get it scanned for codes.