P0300,Random Multi. Misfire Code HELP

I have a 1996, the wires were about 7 years old, plugs were about 3 years old, 3 coil packs are originals and one was replaced about 7 years ago.when problem occurred I was headed up state about 200 miles away from home about 160 miles to location the service light began to blink the engine choked a few times and then the light stayed on, drove the rest of the way there and back home (had no choice). got home and 2 codes the p0300(random multi. misfire) and another cant remember number but had to deal with EGR. Fixed EGR problem and stuck on P0300 issue. I have replaced the wires, plugs and one coil pack(the one that was replaced about 7 years ago) due to one of the male connectors having rust built up on it. ALL replacement parts are AC Delco. Not sure of what to do next any help would be appreciated.

Does the misfire happen at idle, or under a load, like at 50-55, while lightly accelerating up a slight grade?

Was coil output checked on all cylinders with a spark tester?

A good scan tool would narrow it down to which cylinder(s) is/are misfiring....

Idle is alittle rough, and at low speed, as leaving from stop sign as eg. And then again at around 30 to 40 then smooths out. Don't have a spark tester. Had advance Auto scan it with one of their 300 $ scanners and same code p0300.

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Like I said, life would be easier with a scan tool pinpointing which cylinder is at fault....

Spark tester would check coil output.....even though plugs/wires were replaced, you don't know if you have good spark.....could be a coil or even an ICM.....

If spark is ok, we may have an injector problem, MAF problem, vac leak, etc

4.0

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