hi folks

i have a mk4 escort cabriolet with a zvh turbo in it.the bottom end is a 1.8 zetec.

my problem is when im driving alond it will somtimes backfire and cut out completely..it will idle for ages with no problems.it varys between instantly doing it to 10-15 miles before it does it.

my first thought was the alternator as it was a duffer so put a new one on and its still doing it.then i thought it could be the pink fuel pump relay but thats a ok.i have done an inspection around the engine bay and everything is tiptop.the only thing i can really point to is that the engine gets hot,really fast(is this normal?)my temp gauge is knackered so its hard to tell the actual temp,althought the fan DOES kick in when its soposed to.if the car is too hot could this cause the backfire and cutting out?slso it does it with out the engine under boost.its running at 0.5-0.6bar of boost.whats that in psi?.lol
any help would be fantastic.
car spec as follows....

t3 turbo
larger actuator(not sure what its off....cossie i think)
rs turbo head
1.8 zee block
piper fast road cam/pully
195 chip
custom 3'' strait through exhaust coupled to a seirra cossie 5'' box.