1995 Ford F-250 • 172,000 miles

Ok I have a 1995 F-250 5.8L Windsor, I am getting wide fluctuations on my dash regarding the temperature. On the dash the gauge will go from N past the L on the Normal written on the gauge. Parts that have been replaced over the last 6 months: -Waterpump-Hoses-Serpentine belt-Temperature sending unit-Radiator cap- 2 Thermostats (thought that was the problem)-Fan clutch. At idle the temperature is relatively stable, under load running down the road the gauge will fluctuate from the N to well past the L on the dash gauge. It has never overheated short of a bad sending unit I am at a loss. Any help would be really appreciated. Kindest Regards Chris.
January 26, 2013.

Check out the related content below while we wait for the question to be answered by a professional mechanic.