ok

starts with

i get the car back yesterday after bottom end rebuild, and its running mint

i drive it until 2 this morning on a "running in drive" (with thin oil in), and its mint and drives sweet for 350 miles
get in it today and all is mint still

then about 6 tonight im having a little clean in the engine bay and notice a jubilee clip loose...

so, i take the air box out and affiliated hoses and refit to make absolutely sure they re all tight...

now....im absolutely 100% positive all connections and pipes are how they should be


sooooo
the misfire starts AS SOON as it even sees a bit of boost...
and its a massive misfire
if i rev it to 4k without it coming on boost, then its fine
but the second it comes on boost, massive misfire again....
it also seems to be down on oil pressure slightly....
but apparantly the gauges arnt to be trusted
what the fuck is it???????

its a nissan skyline gtr by the way