HELP!!2001 Isuzu vehicross ironman edition
 

I've had this faithful rig since 2007. Never had it left me stranded or confused. It is now in its 3rd mechanic shop leaving them all scratching their heads. December 2018 I took it to get a Christmas tree, it started up and ran as usual but then about half way to my destination it acted as though it was struggling for fuel. Very chuggy rough driving. I got to my destination shut it down, went and cut our tree. Started it back up, it idled ok so I continued down the hill. Once I got on the highway I really had to apply the gas, this was only about 5 miles from home. I got home, parked it, a few days later I had it towed to the first mechanic shop. He told me I had melted my catalytic converters. I had him replace them. He had it in his shop for about a month. He changed, also, the TPS. He returned my car and said it's still a little hesitant but should be good to drive and suggested that I change the MAF. I did that. No change! Off to the second mechanic, full diagnosis, the first mechanic never replaced the O2 sensors so they were replaced, this mechanic said my MAF was reading high and low voltages, he also found that my check engine light was now disconnected? After about 2 months he returned my car and said try a new ECM. Easy plug n play so I replaced it. Nooooooo change. It's now been towed to the third mechanic. They found 55# pressure at the fuel pump but significantly dropped to 34# at the regulator. They've had it for about 3 months and are also scratching their heads but don't want to give up. Any ideas are much appreciated. Outside of taking it to a dealership. Sorry for the long thread