[dcw]

I can't tell you the exact function the capacitor carries out but I can confirm it is a standard part of the ignition unit set-up.

I have a spare one here you'd be welcome to try if you like - it is part of what, as far as I know, is a fully working ignition unit.

If there was a fault in the ignition system I would expect it to throw up an error code on port 2 of the diagnostics. My first thoughts on that front were the flywheel sensor, which I note you have changed, and the MAP sensor - that is assuming the B18U has one; sorry, it isn't one of the engines that I know!!.

Thinking in terms of eliminating the obvious - and in no way wishing to be rude or imply you are silly or anything, but I know myself how easy it can be to overlook the simple things - what state is your battery in? Also, is your air filter clean and not clogged? You say this appears to be a problem that is gradually getting worse, and hence a failing battery came to mind. Have you put a voltmeter across it and checked its charging rate etc?

If you'd like to try the capacitor though just drop me a PM with your address and I'll send it up to you. Won't cost you anything so might at least be worth a try?

All the best

David