Porblems when started from cold

Hey all. Problem here im hoping someone will have advice for. Few months back my dreaded timing belt snapped on my 2001 156 selsespeed. Anyway got new valves in and new belt on, timing set etc etc. but now when you start her from cold, she jerks and almost conks out for the first 2-3 minutes, til she heats up. Had it i at the mechanics, he said could either be cold start sensor or needs new sparks as he says it feels like she isnt sparking onto the cylinder properly, all sounds foreign to me. any ideas?

cheers,

scotty