93 1500, 4.3L just starting to run rough

I have a 93 1500 with the wimpy six and 180,000. It has just recently started running a little rough on cold start up. The idle goes up and down, but it clears up quickly. I've also begun to notice mild surging when driving it. It's slow to a certain RPM and then surges forward. Nothing big yet, but it will be some day. In the last year for one reason or another I've replaced:

fuel pump and filter
distributor cap, rotor, ignition coil, module, wires
EGR valve and solenoid, PCV valve.

I have these weird spark plugs with three electrodes I put in about 40,000 miles ago. They looked OK the last time I checked them. Any guesses?