New member here and glad i found this informative site!
Anyway, i bought this van 2 months ago with the sec light on, since then the fuel pump and alternater went out and replaced also changed plugs, wires ,rotor, cap and air and gas filter. It seems now the sec lite comes on intermittently. After i hit 75 mph it comes on flashing then when i slow down it stays on steady. then other times it will stay off! It seem to trip after i hit 70 mph approx. Other then the lite comming on the van runs great! any ideas would be appreciated! thanks, joe

p0300 is a random missfire, based on what you've done already, go back over your ignition system and make sure everything is tight, routed properly, and pay special attention to the cap and rotor. What brands of wires, plugs, etc. did you use? The right brand of parts will make a differance.

JOE OZ..... Be courteous, and report the Solution to your Problems with your vehicle!! I had a similar experience,and it was the COIL

Absolutely, Ihavn't had a chance to do any further testing, I would like to know how you determined it was the coil? thanks, JoeOz