1997 Chevy Cavalier 97 Z24 2.4 engine no power, check engin

Hi. I was driving home when the car started acting up. It seemed like it slipped out of gear on the expressway, was unresponsive when given gas and then stalled when I stopped at a red light at the end of the exit ramp. It smelled like something burning.

I got it started, it sputtered and had no power, I had to finesse it to keep it going. I took it to Auto Zone to get the computer codes checked.

They pulled a code P0300 code from the computer. I changed the plugs and both coils and it made no difference. They checked the ignition module and it checked ok, though they said it was starting to heat up. It seemed to run a little better once the engine had cooled off Any ideas would be greatly appreciated.