Hmm, dunno if your truck has points or not, maybe not. Check your manual to see if it does. The points are in the body of the distributor under the distributor cap (pop the cap and you can see 'em in there), and open and close as the distributor shaft turns. We have an '81, and I don't think it has them, but we HAVE gone through several gas filters with GREAT success in running afterwards. Now I am just finishing up the process of replacing the fuel tank, it had plenty of rust and crud, with another one which I've had "boiled out" chemically, to eliminate the source of the problem.
A number of guys with older Luvs have told me that having to replace the ignition points is a common problem, with excellent results also. All vehicles used to have them. If it dows, then replacing points is a common service item, to be done when you do a tune-up.
Here's a link to "how stuff works" which has a pretty good generic picture of points, so if you have 'em you'll know it (scroll down their page to about midway):
http://static.howstuffworks.com/gif/ign ... n%26sa%3DG
If link doesn't work, cut and paste the URL into your search engine.