Hi, hoping it's a simple issue...

New to me 1600cc aircooled 1979 T2 commercial converted to a camper. Had a recon engine 4 years ago and has only done 1700 miles on it.

Picked it up yesterday, ran fine until it was warm and under load (ie going up hill), when it misfired, occasionally backfired and ran out of power. Would take 4 or 5 attempts to restart over a couple of minutes and would then run fine for another couple of minutes.

Appeared to be fuel starvation, but has a clear fuel filter and looks like the flow is fine. Has a single solex carb recently fitted. Got through mot recently with the new carb on.

Any ideas?

Also, anywhere recommended for maintenance/ servicing near Weston / Bristol area?