Backfiring and smoky smell

[Sugar Spun Sisters]

Last week on a 30 mile trip camping the van backfired twice...loud bangs both...slightly lost power for a nano second. On the way home, a slight loss of power again, for a nano second, but did not misfire as far as I'm aware. 20 miles from there, get home, get out of the van, get back in to take all our gear out and there is this burning smell, not fishy, but just like a smouldering, smoky smell. I traced it to behind the dash, behind the clocks. I thought the wires might be burning there, but I couldn't see much as brake fluid reservoir in the way, but the smell was defo coming from there. I haven't taken the van out since, and the van hasn't gone up in smoke but wondering if anyone can shed some light on this very scary, strange experience?

[72BUG]

Petrol? Diesel? Aircooled? Wasserbox? A little more info on the van may be useful.

[Sugar Spun Sisters]

Ooops, sorry, proper info...1.9 petrol DG watercooled 1984.
Hope that helps anyone who can give me advice and prevent me from taking the van to the garage. It also had a full service with all serviceable parts, new fuel lines etc in May and in September has done 1200 miles to Cornwall and back without a hitch.