Got er fixed
After changing the crankshaft sensor it started right up. Also replaced the plugs, new fan belt, new electrical connector at crankshaft sensor, and replace the heater hoses. Those heater hoses were leaking a small amount of anti freeze that was going into the spark plug socket and causing the number 8 plug to foul. Also, when I changed the spark plugs I cleaned the spark plug sockets in the head to get rid of a lot of oil and debris that had accumulated over the years. I used a combination of WD 40 in the sockets, a cleaning brush and rod for my 12 gauge to brush out the debris, rags wrapped around the brush to clean the debris, and a shop vac. I was able to get most of the debris removed and only a little got into the cylinders. I torqued the plugs to 21 ft pounds and they should stay that way for the remaining life of the truck. Also put electrical grease on all the plug wire end to make sure I keep a good electrical connection.
As a final repair, I was missing the weather strip between the cowling and the hood. As a result, dirt, leaves, and of course, water easily got into my engine compartment and made a big mess of my engine. My local truck salvage yard sold me a weather strip from a similar F150 for $10 and I have solved my problem. This also makes the truck a little quieter in the cab.
The bottom line is the truck runs like a new one even though it has 152,000 miles on it. I'm now thinking I should have it painted. I could then buy me a camper trailer and stay in camp grounds as my bride and me travel around the country in our retirement.
PS I also changed the speed control to fix the problem of going faster than the speed indicated by the speedometer. It seems to have fixed the problem but I have not had an accurate recheck against my GPS to make sure. The new speed control was only $21 at Autozone and only took me about a half hour to change.