I was out last night for about 30 minutes and once the engine was properly warmed up I started accelerating harder. Suddenly at about 5-6,000 revs the engine started half cutting out / misfiring/ losing power and the tachometer was all over the place- up to 9,000 and then down to 2,000 even though the engine was probably only running at about 3-3,500. I slowed down to 30 and it recovered but then did the same when I accelerated hard to about 60 again. Any ideas what the problem might be. Last time out was at Castle Combe with the L7trackday where I drove it to the rev limiter and it didn't miss a beat all day? Might it be a lamda, TPS or MAP sensor problem? thanks, Neil