He who dares Rodney, he who dares.

I had exactly the same issue on my first track day at snetteton.  I got some 50mm riser plates made (I think I may have spare set if your interested) and the only issue then I had the next time was the sidestand scrapping at serious lean angles. Check this YouTube link https://youtu.be/igCqYtugfp0. Apart from the riser plates everything was standard except I dropped the forks through the yokes 25mm.

Hi Harry
After following me for we came into the pits and he pointed to me and he commented on my riding. He'd never seen someone ride an 86k mile bike with such commitment and skill. He asked if I'd ever raced I told him it was 2nd track day, he was a top bloke offering some good advice. He felt with a proper track bike I could have been quite good. Back in his garage he told his partner at MotoVudo to watch me in the next session. I was getting some serious lean angles, my side stand was hitting the floor on the left and the exhaust clamp on the right. Hope you liked the videos.

When the problem happens check the exhaust down pipes. If one or two are cold it is more likely to fuel starvation due to worn diaphragms. Have had the same issue on mine at 86K miles. Bought a replacement set of carbs from fazer spares for £40 problem sorted.

I have cleaned my carbs and also cleaned a spare set just in case.
I got 2 cans of high pressure spray carb cleaner from halfords, 4 plastic dishes and small wire file set from eBay.
Using a screwdriver that fits really well remove the fuel bowls and take a few pictures on you mobile so you see how it all goes back together. Place all the items per carb in numbered trays with enough carb cleaner to cover all the items. Using the spray clean the main body and let dry. Now clean, gently using small file all the jets etc.
If you are removing the diaphragms also beware the top covers can be tough and a good screwdriver is essential. Check the diaphragms to see if they are loose or baggy as this can cause poor running, misfires etc. I purchased a second set of carbs from fazer spares for £40 to replace mine.
If you take you time initially you will find this a simple job that makes a big difference.

Hi There I have all the issues you've had I changed coils, caps, plugs and air filter. I cleaned the carbs, tried redex, the lot. My 98 fazer (88,000 miles) would be ok for s few days then misfire and you get one or two cold downpipes. After cleaning the carbs myself I noticed that diaphragm rubbers on the top of the carbs where slack, I replaced them from a set I had as a spare and the bike was back to normal. No misfire, perfect again. Hope this maybe of use.

Did snetterton last year, it was superb. Will be doing again in June or July if they have open pit day and once I've fitted the footpeg risers I have made.
I have now booked Snetterton for June 8th for the full day. Doing both the day and evening sessions. All I need now is a high-level link pipe and some new Supercorsas for my spare wheels.