It does sound like air in the filter, I would put a new genuine filter in first & then start the trial & error or get it on a code reader - could also be blocked EGR
That looks loveley, I did a similar matte black on a polo the other day with spray cans lol. (took about 20m but not the same quality finish)
Also did the wheels a contrasting Gloss back at the same time :P
There's now way to do that unless your the police.
This one is white (if you squint hard enough :P) http://www.gumtree.com/p/cars-vans-motorbikes/honda-prelude-classic-1990-stunning-not-civic-or-accord/1017555888#photo-content