Thanks for your input guys. I searched for all the grounds I could find; the mounting bolts in the bottom or the engine, the battery ground and the small connector, and one other small relay mount on the top of the frame near the hydro pump. Can not see anything attached to the started. What has been done; new O2 sensor, cleaned to bare metal, new plugs, inner and outer air filter, inspect and clean all connectors that I could find, new fuel filter. Then when i just could not get it to run properly, broke down and took to dealer. they kept it a week and all they found/fixed was change the fuel filter. and discovered that I had re-installed the inner filter element backward( I know i had that thing apart so many times, just got sloppy)they changed and said it ran fine, and no codes. I know that my screw up only cause problems right at the end because i had run it with no element to see what effect it had. (only in the garage of course) Yesterday I use the mower, runs fine and got some real work done (work=$), but after about 5 minutes the check engine light came on. This issue has been one for many years but the engine has run fine, and yep now code 34 there again. This is what happens; run full throttle-blades engaged light comes on after about 5 mins, release blades and let idle, within 8 seconds goes out, slow to disengage blades and back to full throttle and in about same time it goes out. Seems it must be the load causing the issue. Again any ideas are greatly appreciated.