I have a 1995 Chevrolet K1500 Silverado 5.7 TBI my truck as of right now has almost 310,000 miles on it I have owned it since 2010 I have put over 100,000 miles on it.I am always doing regular maintenance every 3,000 miles I change the oil I am always replacing the cap and rotor and plugs and wires.This is what happened it was last October 2018 and my truck was running fantastic nothing what so ever wrong and about a half a mile from home all of the sudden it backfired about 4 really loud times and started running like crap.after it backfired it would barely run you could just barely give it any gas at all and all it wanted to do is just backfire through the throttle body not the exhaust I got lucky and made it home I went through the entire fuel system checked all of the ignition could not find anything wrong.The only way I have gotten it to run at all without backfiring is to unhook the timing advance brown and white wire under the passenger side dash and then advance the timing manually just about as far as the distributor will go and at first it would start and run okay sounded like the valves were going to rattle out of it but it would still run.Now it will start but it is missing at first then after you start driving it it takes until the truck shifts into 3rd gear before it will run just a little better.This truck has never gave me any trouble this all happened in a matter of about 5 minutes or less.Can any help me out does any one think it might have jumped time or is the computer or the distributor any help would be great