really odd squeak/missfiring v8

help anyone ive got a 97 p38 4.0 gems which has a squeak /possible missfire on each bank of cylinders which sounds like its actually coming out of the exhaust ports / manofolds at the back, ive been bald for 20 yrs an i still feel like pulling my hair out, as its driving me mad ive replaced the leads removed the heads an had valves done replaced the cats as you could hear it squeaking inside them replaced the coil pack the squeak gets louder the more throttle you give its a recon only done 30k an had new oil very 5k been thinking along the lines of worn cam lobes , also feel a real fool as i didnt check cam when heads were so im going to do a bit of research before ripping off that manifold again any one had this fault an managed to fix it could be my new friend for life