I have a 4 year old TRX420FE with 6000 miles under its belt. While doing some slow stop-start work with a 600lb trailer the cooling fan was coming in occasionally but no real signs of a hot engine and certainly no temperature warning light. After a while engine started coughing and spluttering and then gave all the impressions of working against a very heavy load. I eventually switched it off as it felt as though it was about to seize up altogether. Left it overnight and then made sure all oils, coolant, air filter and warning lights ok. It started and ran normally as if nothing had happened. Any suggestions as to possible causes would be gratefully received.