3.9 classic Rough running (at times)

Hi to all,

Purchased another classic the other day (looks like overfinch have played with it at some point) but it has developed a fault with the engine. runs fine, lovely and smooth good power etc, but it started to run rough. Then very rough, lost nearly all power and sounded like a bag of sledge hammers rolling down a tin roof. In mild traffic in town.
Then it cleared up and ran fine. (back on open road)

Did it again the other day to the missus. Resulted in the motor being flat bedded home. (taxi run to gatwick airport)

Just been out and cranked it over. coughed and spluttered at first but now running fine.

Just wondering if it could be the amp getting hot when going slow.

Any ideas?

Cheers

cud be mate, cud be alot of things as you know all too well. you could give stu a ring? he might be shut till monday now but worth a try