rough idle

ok I got a 1989 B2200 and it will run just fine but after a while the valves will start to tap for a little while then it will stop... Now after I drove it a little while it started idling real rough shaking the whole motor.. It has new plugs wires and oil done recently not even 500 miles ago... It starts to do this from time to time but normally stops shortly after... Also when it sits a while when i start it the damn thing smokes for about 20 seconds or so then stops but doesnt smoke when driving.. If anyone can help let me know thanks in advance...

The smoke is most likely the valve seals worn out letting oil past when they get cold when they warm up they seal. Have you changed the fuel filter that might cause a rough idle.

nah I havent changed it since I have bought it but it only does it every once in a while I just drove it again and it didnt do it... But I have noticed a difference in the way it runs since I just put a new thermostat in it.... anyone else have any idea why it would run like this???

Yea, it sounds like the valve seals to me too.