THE PILOT ENCOUNTERED HIGH ENGINE OIL TEMPERATURE AND A ROUGH RUNNING ENGINE DURING CRUISE. HE ELECTED TO EXECUTE A PRECAUTIONARY LANDING TO AN OPEN FIELD AND CONTACTED POWER LINES DURING THE APPROACH TO THE FIELD. THE PILOT STATED THAT HE COULD NOT SEE THE POWER LINES DUE TO THE BRIGHT SUN. TEARDOWN AND EXAMINATION OF THE ENGINE CONFIRMED PROBLEMS WITH THE IGNITION SYSTEM AND THE ENGINE LUBRICATING SYSTEM.