1997 Questions for all other cars MGF 1.8

Hello there, I have had the mgf for round 4 months occasionally would not start first time but generally it's quite a good little runner, anyway. Last sunday car would not start after many tries. Eventually it started and off I went only for it to cut out within a few metres. Tried again and off it went, was driving round to find a garage open but nothing, the car did cut out a few times during this time. On monday got towed to a garage, they changed the pick up sensor and the coil (sorry if im not more speciffic!)Also had a water leak it turned out to be the thermostat, and replaced the back tyres as they were almos bald! (Might aswell as it's there), so got it back on wednesday afternoon and seemed fine. Next day cuts out as im approching round about, after a lot and of lots of tries it started, it cut out a further 2 times before I reached home. This morning set off to work ok, it's 6.7 miles from my house. The car cut out round about the 5th mile, and coming home wsas a disaster! Took me 2 hrs! Car wouldn't start straight away would cut out within metres! Wat do you suggest this is about? The car has had a thorough look over and the diagnostics computer was used and watever faults showed the mechanic fixed, and still the problem remains, HELP!