at part throttle, mostly from a standstill or rolling stop i will get what sound like a muffeled backfire. its a single pop that sounds like its coming from inside the intake manifold. valves are not out of sink and i backed the timing of a little too. that did not help. has any one else had this problem, and what can i do to fix it.

 

You backed the timing a little meaning retarded it? If i'm correct advancing it would help you out with that. Also, have you checked your wires? I was having this problem and all I needed was a tune up, mainly new wires. The old ones were splitting causing spark jumps. Check under your hood at night with the car running. Look at the wires and look for blue sparks. I'm pretty sure bad wires can cause a backfiring sound from the intake.

 

Mine was doing that, and it ended up being one of the rocker arm studs was pushed up out of the head a little. (Not that unherd of with hight miles)