I just claened mine this weekend with the electronics parts cleaner. The one before the cat was very black and sooty. I just hosed them with the cleaner (into a plastic bowl) let it sit, then hosed then again and again using the brush attached tothe cleaner as well, until they were clean. I then left them in the sun to dry for an hour before reinstalling. I too am hoping this will cure my very poor mileage of 16-18 for the 4 cyl.
Be sure to soak the
[email protected] out of the O2 sensor bolts with WD40 or Liquid Wrench, before trying to remove them, most are 'welded' on with rust.....
I'll post again in a a few weeks to update on my mileage gains, or lack there of......