Odd Misfire

[Nattman82]

Well, so far ive had about 2 weeks trouble free Silvia ownership but as is the way with old cars the problems are starting to creep in. First it was the O/S Ball joint but ive got them on order so no biggie, then it was uneven/lumpy idle but thats oddly gone, now its a fecking pain of a misfire. Basically, under full throttle conditions, the car pulls like a train, no hesitation or misfires. But, try to drive normal and fml its a nitemare, made worse by the fact its an auto. If I drive under 3000 rpm it wont accelerate smothly, put it under any kind of load such as to speed up a few mph and it misfires like a pig, get it past 3000 rpm or give it more than half throttle and its absolutley fine.

So to sum up, anything under half trhottle and between 2000-3000rpm it misfires, anything over these and its spot on???
Its had new plugs, rotor arm, dizzy cap and the leads are decent magnecor ones. Any ideas guys?

Its the CA18ET engine fyi.