Been there.Obviously it helps to have your gaskets on the right heads.
Try it with long tube headers bolted on. Have to play jenga/tetris while doing so.Thats a two person job
Well, I'm somewhat leaning toward what I might call the "ultimate cat cleanout" that involves wiping a smear of acetone on the end of a wrecking bar and gently dislodging the buildup, which might have the side effect of loosening the honeycomb . Just looked at the codes again and it has 8 "Heater Control Circuit" codes that I originally dismissed as something to do with the HVAC. Clearly the oxy sensors are all toast as well since the carb cleaner doesn't seem to have worked it's usual magic on those.Your description certainly sounds like there is a pretty massive back pressure in the exhaust system. If the cats. are really caked up with oil and other crap, I doubt you'd be able to burn it all off any time soon. I don't know whether any "non approved" cleaners like acetone or tolulene will further ruin them or not. I know they make cat. cleaning stuff, but I have no idea whether it works or not, or will it work on ones that are super gunked up. If you don't want to dump more $$$ into it, you may want to gut the cats and leave them in place......if you feel the emission nazi's wouldn't catch you. Otherwise, once you've verified it is the cats. causing the problem, you may want to spring for some new ones.
Please keep us posted.
Um, the plan is to thoroughly clean them out, make them so clean they are see through I dropped the 2nd one yesterday, will give it the same treatment then refit.So, now why not gut the other one too, put it back together and see how it runs??