After my 94' 4.3 4x4 auto has been run on a good 45 minute trip, it misses bad and sometimes stalls all the way out. The weird thing is, if it stays running then it runs like crap for about a mile. Here's how it runs when it's acting up. It first starts a small stumble but then after a few seconds its like its not even taking fuel, I'll give it more and more fuel but its like I cut the key off, nothing happens except backfire if I press the gas too much. Okay, this all can be corrected for a few miles by just letting it die or cut it off myself and cut it right back on. Idk if its related but several times that it happened, the temp went from normal (halfway between 0 and 210) to a tad over 210 but after the episode the temp went back to normal. New: plugs, oil change, rad flush and coolant. Me and Dad put this 135,000 mile motor in last month and it ran perfect til his started 3days ago. Any thoughts? Distributor...? Some kind of temp sensor..?

 

Check the fuel pressure, the vortecs are know to have fuel issues either leaking from the spider or fuel pump. Also check for vacuum leaks. Pull a few spark plugs and see what they look like. Rich and black soot? or lean and white ashy residue? Are all plugs fouled the same? you can avoid checking the #3 becasue it's a pain to get to but if you check the other 5 then it would give a good readout of what to look for. I am assuming this is a vortec Vin: W and not a TBI engine.

 

Yes it's vin W and no, it's none of the above. I just got finished doing everything you listed. Good points, but none were my issue.

 

Under the throttlebody you will find your egr, near that there is blue/red wires going into the intake. With engine running, play with those 2 wires. They are your injector harness wires, and the cheap plug on the injector is another known to go bad part.

 

Nice, thanks dude I'll check it.

 

But how did the plugs look? what was fuel pressure running? not running? what was vacuum pressure? Were all plugs the same or was specific ones different. I noticed new plugs and they may not have any indications, so how were the old ones?

 

All of that is good but the old plugs were burnt. The electrodes were melted down like when they burn hot, I mean. Thats why I thought the distributor was bad.

 

Have you checked your ignition timing? maybe too advanced? I'm not used to seeing faulty ignition parts burn hotter.

 

Will do. Tomorrow.