i had the same problem with my lancer.
now i am far from a car expert but it turned out to be the rotor arm in the distributor. (could also be a problem with the distributor or distributor cap)
It was slightly cracked and was inexpensive to repair but the mechanic said that it could be missing a spark at a certain speed because of the vibrations in the engine, as the frequency of vibration changes as you speed up.
Could be wrong but i think its worth a look

 

Sweet, thanks james, but would this be a prob in all gears or only in first like in my situation.

 

Yeah, thats what I thought too. I'm only relaying the mechanics words here but he said the vibration frequency of the engine at different speeds/revs can cause the crack in the arm to open only at certain points in your acceleration.. Hope it ehlps, probably won't

 

i got the same problem.... used to drive me nuts back when i had 13 stop signs to go through to get to the highway...

it's as if the clutch isn't slipping.... instead it's grabbing and letting go repeatedly and quite violently... only happens in first gear..

it's most apparent when you don't do a FULL stop and try and start while the car is still rolling a bit....

no correlation to temperature whatsoever, can happen during summer heat, winter cold (though in winter you just end up spinning the wheels most of the time), right after getting into the car or after a 3 hour drive...

i tried the whole slipping and heating up the clutch... once even out of frustration i was burning the damn thing alive.... until the smell knocked some sense into me...

it's not a problem anymore since i barely go thru 3 or 4 stop signs each day, but it still does happen occasionally...