1997 chevrolet c1500 engine start and has a miafire

The easiest way to track down a miss fire is to use a pyometer on the exhaust ports to see which one is not firing. When you have which cylinder is not firing you can check and make sure that plug is firing, if the fuel injector is metering, or if that cylinder is low on compression.

Start at the beginning, when was it last serviced? How many miles has it done? Is the engine in good basic condition or has it had a hard low maintenance life? Does it misfire when idling or under load? Is it misfiring or backfiring into the inlet manifold? Check the distributor cap carefully to see if there are any thin black lines from the lead post running down the cap. This is called tracking and denotes a problem with cap or lead. Check all the plugs, should be mid brown outer edge to light brown centre after 15 min run around. If one is different colour or the tip is burned away then focus on that cylinder. Try another lead, certainly another plug but while you have the plugs out do a compression test on all cylinders. If you don't have a suitable gauge then get a buddy who has 'cos its going to take both of you to do it. Make sure the leads are away from your hands when you do it and hold the throttle wide open, crank for a few seconds. Pressures should all be similar and within a few pounds of the spec. If one is particularly low then check the rocker arms for damage. The deeper you get into this the more experienced help you will need. Work methodically and dont just fit parts to get lucky.