Help!! Starting Problems

Bought a 1990 1.8 Clipper Cabby Auto recently. Got it serviced, got the timing belt changed & got the timing set up as it wasn't running right. (I've not a lot of mechanical knowledge so bear with me. :dontknow: ) Apparently the valve timing ?? was well out, the belt was about 5 teeth out. It still wasn't running right but my mechanic mate says this is because I am drawing in air through the thick rubber gasket between the carb & inlet manifold.(I'm in the process of trying to source one)
But this morning when I tried to start it, it wouldn't start at all. It's turning over, but very slowly, then suddenly turns quickly for a couple of seconds then slow again. It is possible the battery is a bit flat as there was a lot of starting & stopping yesterday while trying to get it set up. When it does run it runs ok, & revs up no bother, only when you try & drive it, it runs like the timings well out. Just hoping someone can put my mind at ease & tell me it's repairable & won't cost a fortune to fix, & that I haven't bought a dud. :cry:   
Greatful for any help
p.s. still looking for the carb gasket, any leads??