I managed to take my new MGT down to the field this week and it went for longer than 1 minute!!!!!!!!!!!!!!!!!!!!!!!!!!! Then it got scared by a walker and his dog and decided not too start for 2 days.
The current theme seems to be great fun for between 1-5minutes then chuging and sudden for a long period of time death!

i was tempted by that 8.0 i've got a mgt with a lrp .28 spec 2 but nitro's can be such a pain to get running right

I know the feeling well. All I can suggest is looking at the engine settings and trying them all at the factory settings from Associated. Also, trying a new plug might help.