Steve Bailey

I have a 1995 C1500 with the 5.7 and 84k original miles. I got very low on gas at one point and filled it. After a few days it started backfiring. I cleaned the carb and made an appt to have it looked at. While waiting to take it in, it stopped backfiring but kept the appt. They could not get it to do it at all. Fast forward. Ran low again on gas, started doing the same thing. I cleaned the carb and replaced the fuel filter. It seems to do it when giving it gas to pass a vehicle or pulling a trailer. When it is under a load. I did hear at one time while pulling a trailer what i will call valve ticking/timing noise. Timing seems to be good. Not sure where to go from here. Any ideas would be appreciated.