BSAWS6

Car is 02 TA M6. CAM car. LT. Car is tuned HP tuners. Recently car is starting to sputter during load with 4 cyl. like power then backfire at let off. Took it to tuner to log. Guy said its losing cam signal during accel. So he said its either bad ground( i think i checked all of them dont know anyone know where all are), cam sensor, or cam retainer loosened. I replaced cam sensor and checked all grounds i think. I even ran new ground from p.s. head to battery post. Still no fix. Next step is to take front cover off. Does anyone agree. Has anyone heard of this. My brother( a mechanic chrysler though) and I did the cam install. I bought the popular LSX rebuild book and printed from LS1howto and follow all the instructions and tips. I know we used loctite red or blue whatever it called for and torqued to right specs. Could this really be a cam issue. When i did the cam sensor i also took valley cover off and cam lobes(visable) seemed even wear and lined up with lifters. Can anyone tell me where all grounds are. And does the PCM need to be grounded or have a ground. Thats the last thing to be taken out of car for access to firewall gromet for line lock. Any help thanks or if need more info.