Been here several times with this POS, but need it to run for a couple more years if possible???? Last time here I had a fuel pump problem that we apparently got solved. However my last posting was something like engine dies "at WPO", which was a typo and should have been WOT. Well apparently I did not get that solved with a new fuel pump. Several days at about 50 mph the truck started running ragged backfired and actually exploded the muffler! I hobbled, lurching and jumping cutting in and out until I got it to the garage. Next day I started it up and it idled ok but w/o a muffler it roared a little. Again when I stomp the accelerator it will die unless I let up on it and ease the accelerator down and then it backfires. So it appears somehow I am getting an unburned gas build up flowing into the exhaust. I cannot find a vacuum leak, I reset the timing using a vacuum gauge, compression check low but within range on all cylinders. Now again I need some help. Vac reading is a vibrating 15-16 and I am in Denver at about 5,000 feet.