Cuts out under load

I have a 1998 gt with a Vortech v1 supercharger, It Ran ok when I got it, ran out of fuel then the alternator went out. Since getting it up and running it now just cuts out completely under any kind of load, revs fine when not in gear. I’ve checked fuel pressure, replaced all vacuum lines, checked grounds I can see, replaced the FMU, in tank pump, fuel pressure regulator, cleaned the maf, new alternator and battery and it still cuts out under load, wideband says it’s going lean before it cuts out. Don’t know if this is related but it also randomly will drop rpm to about 600 -700 almost stall and then rev itself at idle to about 1200 multiple times. Only sometimes, Sometimes cuts throttle randomly. Please any help or insight would be greatly appreciated. Thank you

Hi John, Thank you for the response. Apologies for the late reply. So I purchased the car, which only has 94,000 miles and two owners it had been sitting for about a year, (second owner was a production company purchased it for a photo shoot and never drove it) i drove it back home, I noticed a slight miss but still had power and idled fine, when out for a drive in negligence I ran it out of fuel and coasted into a gas station. I put gas In it, went to start it and it was dead, fortunately I had a jump pack in the trunk, I hooked that up and it started, on the drive back home It was not charging at all, it was slowly dying, got it home, tested the alternator at the parts store, tested bad, got a new one and new battery as that was also 9 years old, had the new alternator load tested and it was good, at this time I replaced fmu, fuel pump, pick up sock in tank, in line fuel filter, fuel pressure regulator, none of which are adjustable, the tank looked clean inside, no debris, I did not check fuel flow rate. I checked spark plugs, fuel pressure which remained the same, cleaned the maf, and the iac, checked spark plug condition and gap and coil packs. After this it has not been the same, it will go lean and cut out under throttle yet there are no misses I feel gently cruising around town, pulls fine up to about 50 percent throttle. It will sometimes randomly will dip and raise idle, or at cruising randomly cut in and out very quick for about 4 minute on and off. I’ve gotten no check engine lights at any time, UPDATE yesterday I did run a scanner on it again and came up with continuous error po230, po231 - primary and secondary fuel pump circuit (which I’m guessing may be because I unplugged the inertia switch to bleed pressure when working on fuel system) also got KOEO po605 Powertrain Control Module read only memory Error. Which you stated the cpu or tune may have been corrupted when the alternator died. Hopefully this is not it, as it came with no tuner, I’ll look into near by tuners in southern Ca. I will also view and record live date readings soon, I am currently going through wiring circuitry with a volt meter and test light. I don’t know if this could be a cause, but on drivers side coil pack for the secondary post cylinder 7 it had a big burn mark on the inside and what looks like possibly a very small crack proportionate on the outside, I cleaned the inside and there is now a divot where the burn mark was. I attached a spark tester to it and it was getting spark at idle, will post a picture. Again thank you very much for the response. I’ll try to keep this updated!