My 2005 MDX has 140K. Has been a trouble free since the day I drove it off the lot. Just normal maintenance I preform myself. I'm just a do-it-yourselfer with a regular day job. A few weeks ago it started throwing P0301, 02, 03....etc codes (cylinder misfire). Learned via this form that my valves might need to be adjusted. Sure enough, the Exhaust valves were very tight. After resetting the gaps on the intake and exhaust, replacing all gaskets as recomended, I cleared trouble codes and started it up. It ran and sounded great. No codes appeared. But 2 minutes after allowing it to run, the EVAP canister purge valve started open and closing rapidly, sounding like a helicopter. When I turn the engine off and restart it, everything is fine for about a minute or so and then the purge valve starts opening and closing again. Now the OBD is throwing P0497 EVAP low purge flow.

Any ideas on what did I do wrong with the valve adjustment and what I can do to resolve the code and purge valve from opening and closing? Thanks for you help!