I have a 2007 Chevy Trailblazer and I was driving down the road and the vehicle stopped accelerating. I pulled over and now you can shift from Park to Drive or Neutral but the vehicle will not start to roll it just revs up. If you put the car in Neutral you can tow it just fine. What could be wrong with this?

The alternator wouldn't have anything to do with either of the problems your having ! The key getting stuck in the ignition could be a problem developing with the lock cylinder . Can you turn the key to the off position an then it won't come out ? Or it won't turn to the off position an then not come out ? There are safety devices in place that won't let the key come out if not in gear an foot on the brake pedal etc... electronic an they do fail . Electronic Park Lock (EPL)/Ignition Lock Cylinder Control Actuator:Linear Shift Assembly: If the vehicle is equipped with a column mounted gear shift, it has a linear shift assembly on the steering column. The linear shift assembly has a cable that runs from the linear shift assembly to the ignition lock cylinder case. The purpose of this cable is to prevent the ignition key from being turned to the OFF position when the transmission is in gear and the vehicle may still be moving. The linear shift assembly cable contains a pin that is spring loaded to mechanically prevent the ignition key cylinder from being turned to the lock position when the vehicle transmission is not in the PARK position. If vehicle power is lost, and/or the transmission is not in the PARK position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column.

Now for the stall at stops , Your vehicle has Throttle Actuator Control (TAC) System ,electronic throttle control or drive by wire ! It is electronical controlled .
There are sensors in the gas pedal an on the throttle body ,they are connected to the PCM/ECM - engine computer with wiring ! There is a DC electric motor on the throttle body , this is what opens the throttle plate . Throttle plates do become dirty with varnish an stuff that can cause idle problems ! There are videos on youtube showing how to clean a throttle plate . How to Clean Throttle Body 2007 Chevy Trailblazer

Sounds like the physical movement of the linkage is pulling or rubbing the harness. Get up under the dash and see how the harness is located.

You have a slipping transmission, if the fluid is full then you will need to have the ****** removed and rebuilt.

chances are the shift cable is broke at the transmission, I drilled the rod out of the shift lever and ran a shoulder bolt through the shift lever and cable end and finished up with a lock nut.

Can you disconnect the cable from the trans to see if the problem is in the shifter or in the transmission ?

just like the armstrong siddleys from when i was a kid ,they had a freewheel device which was mechanical but this is electronic controlled and without a circuit of the computer ECU i couldnt say but somewhere their is a sensor that is reading the RPM and if i knew what it was and how then overide it ,ask dealer if they can do it for you

2002 chevy trailblazer on neutral mode, trailblazer can be pushed easily,but shifter is stuck on park. vehicle will start.the push button on shifter will not engage

The park shift lock needs adjustment. The solenoid that locks irt inplace maybe the cause of this

More like a brake binding on , this will pull the car to one side like a flat does.

When you hit the brakes to stop, the caliper piston may be going back and allowing you to continue till it gets hot again and starts to bind

CHECK THE BTSI SOLENOID ON THE SHIFT LEVER, IT MAY HAVE BROKEN.