1987 Chevy Silverado is knocking off



I have a 1987 Chevy Silverado 5.0 liter truck that will knock off after it warms up when I come to a stop. It only does this while in gear. It is worse when the AC is on. I had new plugs and a new distributor put in. Also a new O2 sensor, intake gasket and rotor button put in but this did not help. I had a friend recommend a back yard mechanic who said he installed a new torque converter. This did not help. What do you think?