
Originally Posted by
Reptile
It probably should be said that random misifres are common at idle, but random multiple misfires are not, so there is another problem that causes a P0300 code to flash.
I've never messed with a SSM90 kit personally, but I have heard that there are inconsistencies in the machining for the injector seats. That being said, if there were a vacuum leak that was bad enough, you'd be looking at lots of problems caused by lean issues, or even a bad fuel spray pattern. All that together can cause misfires, idle issues, even loss of performance from lots of reasons.