My hes p5 will not idle once it warms up and I am getting

When I 1st fire it up it will idle for ever but after a tank it's a no go. Engine is running well apart from this around 9 mins a tank @ 260 ish on a exergen gun. I have done the usual air leak checks and nothing only thing I have not changed is the mugen fuel tank. Any idea's would be welcomed and appreciated also base needles as well. I've read through the tuning section and watched the novarossi vid and I'm stuck
Thanks again.