I have a 93 jimmy with a 4.3L vortec. several months ago i replaced the fuel return lines under the plenum because of gas inside the plenum. it ran for about 2 weeks until it developed a stall since then i have replaced the map o2 throttle position and tested all other sensors. i have replaced several pigtails and had to rewire some of the electrical(man who owned before me thought he was a car genius but robbed of power and made into a deathtrap whole other story) the mechanic i took it to said the #3piston was blown but that makes no sense to me becuase it runs fine till it stalls and will continue to run feathering the brake and gas pedals. replaced spark plugs and timed, half *** check of the vacuum system. have had an ase master certified buddy of mine helping me off and on but it elludes him as well. any ideas anyone may have will be valuable as it is getting close to hunting season and i need my rig ready.