i can do the general testing, i worked as a agricultural mechanic for 2 years and race motocross so always re-building engines. it ain't no vacuum leaks, i recon it is the dizzy or coil, not that much to buy and i can take the old dizzy back to the scrappy and get my £20 back (hopefully) but intermitent faults like this are hard to spot u can't test it propally if it works fine one min and not the other, i'll test the dizzy tommorrow, and coil resistance readings, but can't really test the ignition module. u can get a recon dizzy off ebay for £15 or a new one for £45 coil should be like £10 of somthing, can't really see it being a problem with the carb since i've checked it and it runs ok at higher throttle if one of the jets where blocked it wouldn't be so intermitent, same about vacuum leaks wouldn't be so intermitent, its funny it'll idle fine untill u do somthing like rev it and then it goes all shit and if u keep on reving it sometimes it fix's it, really funny sounds like the dizzy the magnetic pickup sensor could be a bit buggered or somthing. i'll fix it eventury, car seems to bog down a bit aswell recentally and miss-fire its had a 35thou skim so it could be that the coils not putting out enough power and the extra Compression is blowing out the spark on low throttle / high load situations. so probally best to have a new dizzy and coil anyway. along with some leads, put new spark plugs in it about 3 months back, could do with a cambelt and oil change willl im there aswell. Cheers again bud