Strange problem Legacy Bc5 92

All of the following is happening when warming up

Hesitation just coming on boost but if I power through it everything feels fine. judders and splutters at about 2 to 2,500 rpm

Started it yesterday and it ran for about 10 seconds like a 1.6 carina, no grumble at all and when i reved it there was no dump valve action either it was perfectly smooth but dead quiet.

when i started it last night it was rocking quite badly on the mounts as if it was only running on 3 pots and backfired twice.

when everything warms up its running 100%

I have my suspicions but don't want to influence your opinions. any info greatly appreciated

Have a bit of a problem myself with an impreza which I think is leaning towards having to be re-mapped.

While trying to diagnose the problem I got quiet a bit of info on what causes certain things!

One being vaccum......... You say urs is running a bit rough at idle....loosing vaccum via a cracked or loose line could cause this, which could also be causing the lack of blow off from your BOV. Maybe the vaccum line to the valve!?!

Dont think warming up could correct this tho?!

No probles at idle, runs smoothly

could it be a coil tony
ive 3 spare coils there if u want to swap um around............

Thanks John, Its going down to Huzzy later on today for TLC. i might be on to ya for a coil if thats the problem

the car has been running sweet today and yesterday