[hutcholdschool]

oh the dreaded P0300. I have also been chasing this same issue for quite some time and i have thrown every part at it that I can think of. I also have great compression on all cylinders. So far I have changed plugs, wires, cap, rotor, distributor, coil, spider fuel injection assembly, crank sensor and no change for me. The one thing I found on my truck and I thought it was going to be the issue was my crank sensor had been rubbing on the reluctor wheel so it was gouged out on the crank sensor. I got a new one and shimmed it down so it would not hit the reluctor wheel any longer and that did take away my flashing check engine light missfire but the P0300 still pulls up. I would check that crank sensor if I was you as it is easy to check with one 10mm bolt holding it in and see if it has been rubbing. On my 1997 there is no re learn procedure I have found for a crank sensor replacement but on your 1998 when I used a scanner capable of a re learn on the crank sensor it did pull up for your year but when I select my 1997 there is no re learn procedure available so keep that in mind if you need to change yours out. While researching this issue I found most of the time its the spider fuel injection pressure regulator goes out and floods out the cylinders in the back of the plenum. This issue is easy to diagnose with a fuel pressure gauge hooked up to the fuel rail service port and I think it is supposed to hold at 60psi.