Dustya440,

If you find it's not an exhaust leak, pull the valve covers & check all the rockers to make sure there isn't any cracks or broken rockers at the lifter end. Also look at all the lifters, they set in a hole in the head, look for cracks there. The rockers set under the cams & I guess you would call them more followers than rockers.

I have replaced lifters & rockers by loosening the cam stands just enough to get them out. Otherwise you have to disassemble the front of the engine to get the cam chain cover off & remove the chains & remove the cams. If you just loosen the stands, pull the plugs to make it easier to spin the engine by the crank bolt as some times you have to turn it a little to get the rocker out. When tightening the stands back up go a little at a time & snug them up to make sure nothing is binding, then torque them down.