Rough idle after running for a couple minutes?

I bought the truck listed above 1500 w/t about a month ago and it ran great for the first couple of weeks. It recently started to run rough about once a week. I did spark plugs, wires, distributor cap and rotor. That seemed to fix up until about a week ago it started to randomly run rough until you drive it for a couple miles. After that it will idle fine. I drive about 40-50 miles a day. It starts fine and drives fine, it’s just the idle is very rough and it will seem to surge in power and try to shut off. I am at my wits end and if anybody can help, I would appreciate it.