My engine will cutout at times. when it does it seems like its not getting fuel. took it to the local gm dealership and the computer says im fouling out my 5 cyl spark plug. also when it cuts out it will sometimes jump rpms like my foot is on the floor. also at times it will bog hard and repeatedly. ive been told its a bad valve, fuel pump,and....ring....

any answers? will be happy to answer more questions