help... (yes, i searched)

[Kaizen]

ok, here's what happened... a week ago i took off my intake and put the stock one back on to pass california smog check and it passed. so after i get all my registration done i put my intake back on and a few days later i get this strange hesitation at random rpm/throttle angles. also, when i pull to a stop at idle, the rpm creep up to 1500 and stay there. now this isn't like the bouncing idle that everyones accustomed to, cause it just sits there at 1500. no bouncing, no stalling out, nothing. lastly (and most frustrating) every now and then, my car will not start. the starter turns but the engine doesn't turn over. tested for spark and even attempted a jump (just to try everything) and still nothing. but after several tries it will eventually kick over and then run normal. anyone have this problem or have an idea why this is happening??

btw: its a 92, and tune up was done 2500-3000 miles ago.

thanks for your help