chev 1998 pu, torque converter clutch, emissions control

QUESTION: i have purchased a 1998 chev pu it is a 5.0 liter 305 v8 and when i am going down the road it will sometimes sort of like back fire it only does this once in a while but it is driving me crazy the fuel pump is new the injecters where cleaned could it be the maps or ? some times it really cranks over a lot to start to oh new distributor was installed and new plugs whats left code reader gave a 1345 code but they said if no check engine lights were on it was ok Help !

ANSWER:      There is probably an air leak in the exhaust system.  This is the most common source of backfires.  It could also be the idle air control.  If it is plugged up the throttle blade can completely cut off air to the engine, resulting in very high vacuum signal.  This, in concert with the vapor/emissions control system could also cause a backfire.  Another possibility is that the timing chain is stretched.  You don't see this too much anymore, but it can happen.

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QUESTION: i don't think i asked the right question its not really a back fire just a kind of jerk as your pulling or step on the gas then lrt up a little, or just as you even out it runs along at 60 mph perfect but if you change the speed it will buck a little bit just annoying as heck,pu has only 112000 miles on it,has all new exhaust system thanks for your help.

Answer
    That sounds like a defective converter lockup.  Although the computer is supposed to monitor torque converter function it can only monitor some aspects.  After checking all of the mounts, engine and transmission, I would get a good tech to test the function of the torque converter clutch.
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