ignition problem

this just started a couple of days ago, my 1990 GMC 1500 suburban snow plow truck, 350 Cu.In. TBI, looses ignition about 4-5 minutes after start up, (heat related??), then after 20 minutes or so it starts right up again, and repeats the problem,does anyone else have this re-occuring problem and which ignition component is the most likely culprit??.

On the older GM electronic distributors, the pickup module would break a wire after a zillion flexes from the vacuum advance took their toll. They would do the same thing as yours is doing.

I had similar problems last winter with mine, turned out to be the coil.
Brian

Thanks for the tips guys!.:D