I've been having probs with my'90 8v. I've tried just about every thing!! my symptoms are different but a few things to check/try is the arm and cap which are so cheap that you should just change them to be safe! the ignition control module, which sits on top of ecu. the hall sender/dizzy might be a problem but new ones are pricy over £100! so try and borrow a dizzy! have you changed your fuel filter recently? also check for vacuum leaks on all your hoses, as these can cause huge probs. does it happen at certain RPM or Speed?