Hello I have a 89 Chevy K2500 w/5.7 TBI new body style and about 166k on it and the prob that im having is that it is not firing on all cylinders on start up cold and hot and even some times wile is already running stopped in traffic like at a stop light now iv replaced the distributor about 2 yrs ago and put in a cordone reman from the store and I replaced the ignition coil with it as well as the cap and rotor the plus and wires are all new put them in last year top of the line beldon wires and bosh platinum 4 plugs so im just baffled on this problem please help Thanks

 

I have a ’92 K1500 with a 4.3L TBI and had a similar problem. I tuned it up myself and it ran fine for awhile then can the misfires. It turns out that one of the spark plug cables was resting on the exhaust manifold. The housing melted and was shorting out the spark.
Hope this helps.
Good luck.