timing belt changed now will only run at high RPMs P0300 code

[Andrewsafb71]

How do you check the compression? through the spark plugs? What psi should each cylinder be at? Also what is a leak down test? Would the timing being off still allow it to start? I just find it funny and confusing that she starts with the gas being pressed and stays alive at above 3000 rpm but below that she cuts off.

There's so many issues that can cause a multiple misfire. What I did to fix mine was change the spark plugs and that tripped a more specific code a few weeks later. The new code was related to the MAP sensor and, foolishly, after the part came I noticed that the hose that goes to it was completely cracked. That was the only issue. The car has run great since. Maybe a hose broke while you were handling everything.

Fixing one issue may certainly reveal another. The issue may be unrelated to the timing belt, I'm no expert though.

Good luck!