help me please
 

i have an 86 s10 blazer with a built 350 engine. i had the tranny rebuilt. theres a pinging noise that happens when i accelerate from a low speed. i've taken it to many mechanics and cannot find the problem. ive rebuilt the distributor, changed to cooler plugs, retarded the timing,calibrated the carburator and still have pinging and now trucks bogs when accelerating from a stop. does anyone have any suggestions or opinions? all are welcome thanx