1VJ running badly

[Yobbo]

Bit of a back story.
Last sunday was out trail riding,coming home the bike gave a cough and started to feel flat.Pulling up at a set of traffic lights,the idle was sitting around 2500rpm,then dropped back to normal after about 15 seconds.
Bike wouldnt pull properly up top,hesitating and missing.
Also the head temp sensor was showing it peaked at 265 degrees.
It is also warming up too quick,almost like it's running lean.Normally when I get to work,the temp is around 170-180ish,fluctuating between that range.Now it it is over 200 in a short trip.
At first I thought it maybe bad fuel,but it's been too long to be that now.

I have checked for air leaks,nothing.
Pulled the carbs apart,they're fine.
Plug is fine and just to be sure I've changed it anyways,which hasnt helped.

Tonight on the way home,my Trail Tech Vapor speedo was going bezerk,supposedly I'd pulled 13,900rpm,temperature warning lights were flashing.
I unplugged the wire that picks up rpm for the speedo from the coil.This seemed to help with the high idle as it didn't do it in the two test I've done tonight.

The surging,hesitation is still there,plus it back fires between gears and also when changing down coming to a stop....Very big backfires like a cannon going off.

I've been told the check the timing,but a Yamaha shop said don't bother as if thats the problem,the bike wouldn't be running - eg CDI would be dead.

So I'm pretty much pulling my hair out now trying to figure out what the problem is.
Since the rev counter/speedo was going ape shit,could it possibly be the coil then as I've exhausted pretty much everything else.