I finally got my 4agte back on the road yesterday after 3months in the garage, drove it around all day and it ran sweet, then took it out last night and gave it a hammering, all was good. Started it thismorning and drove to uni and it was ####ed, idles rough, but seemed to drive ok under 3000rpm. Anything above that and it would build a little bit of boost, but wouldn't accelerate and wouldn't rev, just make a growling sort of noise, if I held the pedal flat it would kinda surge along picking up fractionally every couple of seconds then dying in the arse again.

Also it does this weird thing when free revving it, if I back off and straight away hit it again, it makes a noise like sidedraught carbs sucking air (from the turbo) and takes a second or two before revs rise. I have attached a video of this, take note of what I'm doing with the throttle as it revs.

I initially pulled plug leads off one by one and identified a dud plug, pulled it out and sure enough it was fouled, I put plugs back in in the reverse order and it was the same plug not firing (ie not coil/lead problem). So I went and bought new plugs and put them in, same problem, except it idles slightly better.

compression is 160psi in all 4. It just seems strange to me that it suddenly started for no apparant reason. The only change was a squirt of octane booster thismorning, which has never caused a problem before...

http://www.youtube.com/watch?v=zpqFyimkzlg

ideas?