2001 Cherokee Sport 6 cyl.
I am a rural resident and on my way to work going up the highway on ramp if I drive easy - no problem. If I step on the gas the cel flashes - it goes away if I let my foot off the gas. Code from OBD II reader is 0300.
I rebuilt the motor about 60K ago and this issue has occurred before (I usually drive like my grandfather). After the rebuild the crank position sensor failed and the problem improved but did not leave completely. The rebuild was complete with new coil pack, cam sensor, crank sensor etc.
Any thoughts?

 

P0300 is a "random/multiple cylinder misfire". For those, start by looking for one common component failing rather than something related to any particular cylinder.

This is a process of elimination and while there are a number of possibilities, start with easy things first and for me that is fuel pressure. For your 2001, you should have 49 psi, plus or minus 5 psi at idle. If you don't have a fuel pressure gauge, many parts stores will rent you one very inexpensively...call around.

One more thing. A "flashing" check engine light indicates a serious misfire and that can and often does lead to the destruction of your catalytic converter. I'd get this resolved as quickly as you can and would consider parking it until that happens.

Good luck and keep us updated!