1997 Chevy Truck NO COMPRESSION @ CYLINDERS 4, 6, 8

THE HEADS WERE REPLACED LAST MONTH. THERE WAS A MISS IN THE #1 CYLINDER, VALVES WERE READJUSTED WITH NO SUCESS. REPLACED ENGINE CONTROLL COMPUTER AND READJUSTED ALL THE VALVES, AT THIS POINT IT WOULD START BUT IT RAN EXTREAMLY AS IF IT WAS OUT OF TIME. CHECKED DIST. TO MAKE SURE IT WAS'NT OFF A TOOTH, STILL NO SUCESS. CHECKED COMPRESSION, HAVE 150 PSI @ 1, 3, 5, 7 145 PSI @ 2 CYLINDERS 4, 6, 8 ALL 0 PSI. COULD THIS BE FROM A TIMING CHAIN ISSUE? ANY HELP WOULD BE GREATLY APPRECIATED!