From the looks of the plugs and the symptoms you have explained and things you found. I would be willing to bet your choke is not working properly. A bad choke will foul plugs in short order and will limit rpm as the mixture will be real rich and air will not be able to flow freely.
Try this, when the truck is cold like in the am after sitting all night.
Open the hood and take off the air cleaner top.
Push the gas pedal to the floor and release then check the choke plate, it should be shut tight.
Start the truck with the air filter top off and look at the choke plate, it should pop open 1/4" or so, If not the pull off is not working.
Let it run for about 5 minutes and look at the choke again once the temp gauge gets up to about 1/4 this may take longer if you have no thermostat. The choke should be fully open. If not then it is binding or junked up.
If you tap the gas at this point the fast idle cam should drop out.
If the choke is binding do not attempt to oil it, clean it with carb cleaner.
Until you are sure the choke is working properly don't waste your time on anything else.
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