Missfire/surge

Any ideas folks
At Rockingham today on my sp1 and on the third session it started missing and losing power then would come back to normal, it did get progressively worse, so much that I came in, didn't feel safe
It was mainly at the Bottom end, it reminded me a bit of the trouble I had with a immobiliser on my road sp that kept cutting the ignition
I'm thinking maybe plugs, coils, lose connection
Cheers rob
At Rockingham today on my sp1 and on the third session it started missing and losing power then would come back to normal, it did get progressively worse, so much that I came in, didn't feel safe
It was mainly at the Bottom end, it reminded me a bit of the trouble I had with a immobiliser on my road sp that kept cutting the ignition
I'm thinking maybe plugs, coils, lose connection
Cheers rob