You could always use rubbing alcohol as a degreaser if you dont want to get into buying a big can of something else. Ive used it in that capacity when I have nothing else, and its worked, although I prefer Gun Scrubber or brake cleaner for that use.
Strip and clean the slide and see what happens. If that was the issue, it should let you know pretty quick.
I really dont know how sensitive Glocks are to having lubes in the firing pin channel, and Im a little skeptical about it being the problem. I shoot at least a couple of hundred rounds through a 17 every week, and have been doing it for a couple of years now. It gets cleaned (basic field strip cleaning) after every outing and I know Ive got solvents and lubes down on the firing pin and most likely down the channel, and Ive never had any light strikes. I stripped the slide once, to replace the extractor and its spring, and the firing pin and channel were somewhat dirty, but not overly loaded up with crud. I cleaned everything with solvent, then Gun Scrubber to remove any residue, then wiped everything down with Eezox, wiped off the excess and reassembled, and its still running fine.
If I remember right, didnt you say in another post that someone had done some trigger work on your gun? If so, is it possible that could be the problem? To take that out of the mix, if you know someone else who has the same model as you, swap slides and see what happens. That should eliminate the trigger issue.
As far as the ammo, Id try a couple of different brands and see what happens. Ive shot a lot of the Russian (rifle) ammo, and Barnaul has always been the best of the lot. Most consistent and accurate. Ive never had any of the issues with it that Ive had with Wolf. Wolf really isnt all that bad, Ive just always found its to be very inconsistent. Some lots shoot great, some really suck. I also usually get one or two "duds" per case, which Ive never had with Barnaul.
Youre still going to have to go about this somewhat scientifically though, if you want to solve the problem. Might be as simple as switching ammo, or as usually is the case for me, NOT.