Engine doesn't run properly! Help!

[Patrice]

The car was working very well until last October when some some backfire noises started when foot off the throttle and also ran roughly etc....
Wrightune in Wallingford change the plugs and everthings was working perfectly until a month ago when the same symtoms came back!

Wrightune did change the mixture and the car worked again perfectly, but same symtoms again!!

Does anyone had this sort of problems? any advise will be welcome!

Also does anyone know where to have a speedometer refurbished!