TE 250 Xflow running prob.

[smlfrd]

Hey guys, my TE seems to be going through periods where it seems to missfire. The symptons are.. Only happens once car is warm, seems to follow a pattern of running fine for 3-4 mins and then will run like a bag of S*&% for about 30 seconds then be fine again for a few mins, and keeps cycling in this fashion. The carby has been rebuilt, plugs changed last service (neither making a difference), all leads are sparking and it happens used: whether the air cleaner is on or off.

Anyone got any ideas where i should be looking next? anyone had this prob before? Any feedback would be much appreciated.

Cheers