I have been having this issue for some time. Have had it in close to 10x now for it, plus what I did beforehand. Most recently the coil was cracked. It had been the first part replaced after all this started. Along the way plugs, wires, cap & rotor, EGR, ign. module, idle control, repair of an O2 sensor wire, etc, have all been done. Ran good for 2 days. Once again today it started to run poorly and the light came on, then ran worse. Eventually it ran better and the light went off again. This has been happening for weeks. Any ideas?

 

Have the DTC's retrieved and post them here in the order they are retrieved.

 

was told random multiple misfire

 

P0300 is almost always caused by a fault in secondary ignition: Plugs, plug wires, distributor cap & rotor, and the ignition coil. If camshaft retard is not within specs, it can cause crossfire inside the cap, which causes the engine to misfire. Low fuel pressure can also set P0300.

These things are real fussy when it comes to secondary ignition parts, especially plugs, cap & rotor. They like AC Delco parts, aftermarket stuff doesn't cut it When installing the cap, put a dab of silicone dielectric grease on each terminal, inside and out. The terminals are aluminum and the grease reduces corrosion, which extends longevity of the cap.

Camshaft retard is checked/adjusted only with a capable scan tool. Desired spec is zero degrees with a tolerance of +or- 2 degrees.

Key ON, engine OFF, fuel pump running: Fuel pressure must be 60psi to 66psi. It must remain above 55psi for at least 10 minutes after the pump shuts off. If it fails either part of this test, further diagnosis is necessary to pinpoint the problem.

 

[FONT="Comic Sans MS"][/FONT] the fuel pump and filter have now been replaced and it is still acting up intermittently. Now they want to replace the spider injector assy. Another mechanic seems to think it's more likely electrical. Everything has been replaced already. The cap & rotor are not AC Delco. They are Duralast Gold I believe. I'm tired of guesswork and it's been very costly. Ignition module and coil have been replaced also. IDK what's left. I think a leakdown(?) was performed. The fact that it comes and goes is perplexing. There is a bit of a pattern to it. Need help before I spend way too much

 

You don't need to pay a "mechanic" to guess what the problem is, anybody can do that. At the rate you're going, the parts store will run out of parts, and you'll run out of money. Is this something that you would like us to help you diagnose? If so, post #4 explains 3 things to check, let us know what you find and we'll continue if necessary. We already know one problem with it, Duralast distributor cap, install an AC Delco.

 

it was the spider inj. assy. causing the problem all along. Motor runs greaT now. Did have them replace the cap & rotor first. Wish I could've done it myself again, but too cold out. Thanks for your help