need some help please
 

ive got some problem with my scooby...car is running sweet most of the time but once a while revs are playing up and down thats about 100 up and 100 down and then is running fine for a bit again... when is playing up im getting slight valve rattle(sounds like valve rattle but im not sure could be a coil pack playing up)and then when it settles is quiet again...and the main problem is when i accelerate car goes fine some times but oter time im geting massive back fire and i dont have any boost from the turbo after that until ive switch the engine off and let it stand for a bit... Any ideas what could cose that...
thanks

sounds to me like one of the following, a possible lamba sensor given up the ghost, overboost causing fuel cut, and an idle control valve being in need of a damn good clean / replace, r u gettin engine check light at the same time..?

p.s what car is on and what mods?

is a classic wrx n-reg td05 16g fmic decat remaped polished and ported inlet apexi filter...i dont get the engine light flashing but i noticed it started to happening after ive changed timing belt and i do get bit of oil on outer turbo casing between inlet and exhaust side of it...car was serviced about 1000 miles ago...ive cleaned maf sensor and air filter...i wonder if inlet manifold gasket could make it going loopy (ive had inlet off just before ive done the timing)

car is boosting 1.2 bar now after remap

in which case mate, if i was u i'd check the intake pipe where it joins the turbo for splits perished etc as this is what just let go on mine and i then had some oil splattering on turbos face as well, ( did u replace the gaskets with new ones if not the its possible, find a local garage that can do a smoke test, will find any leaks. )

ill do that thanks for advice Martin

no worries mate.