hi guys i have a 69 tbird with a 429 thunderjet engine with c6 trans. ive spent he last few years getting her back on the road - i live over the pond in england so its been a long wait- well i just got her onthe road last week but shes started missfiring but only when idling or very low revs. its ok when im driving but when im stationary or going very slow the car feels lumpy etc. have checked all the plugs,leads, distributer cap and rotary arm etc - theyre ok.

any ideas???

as far as i know it runs on leaded petrol but i have to put unleaded in and then use an additive - could this be why???