Jpaz - when you first experienced the problem, were you just cruising along, or were you pulling uphill or accelerating (pushing RPMs above your normal cruise RPM level)?
I had a similar issue last summer, and it drove me nuts. it would start and idle fine, but at speed or accelerating above 2800 to 3000 RPMs would chug and sometimes die. I thought maybe bad gas, clogged filter, bad fuel sender, all sort of things - All the "normal" troubleshooting items yielded no luck (I had fuel, spark and air). I blew out all my fuel lines, changed the pump and sender, fuel filter and even the carb. All with no change.
I spent the better part of three weeks trying to figure it out. Turns out that just prior to the problem surfacing, I had put my new FMX in, and during the installation, I had somehow accidentally put a bend in the the fuel line behind the shock tower. Probably hit it with my elbow while loosening the old bell housing bolts. I couldn't see the restriction until I pulled off the wheel and looked from inside the wheel well. It had just enough restriction to starve the car of fuel at certain speeds. Three weeks pf pulling my hair out and it took 15 minutes to bend and splice a new section of line in.
So not saying it isn't bad gas, but just wondering if anything else was done to the car just prior that could affect air, fuel or spark at certain speeds (even inadvertently). Just some food for thought.
