I replaced the camshaft valve cover gaskets and the O2 sensor last weekend. One benefit of the new O2 sensor in that the rough idle appears to be gone. Let's hope the the new valve cover gaskets fix the oil leak problems. Would be curious to get it tested but I think I have more work to do. How difficult would it be for a relative newbie DIYer to replace the catalytic? The O2 sensor primed me a bit for the exaust since it was a PITA to remove. Needed to get a propane torch and heated it up so it would break free. I assume the catalytic R&R would be more of the same...