jeep sputtering/putting. quick advice?

74 just started sputtering/putting once it warms up. It takes probably 20 min of driving for this to start. When you first start it up, you can zip off without waiting, no problem, but after 20 min or so the tach needle starts bouncing violently. This is probably due to a distributor cap? or condensor? plugs? Or could it be.......oh no........head gasket?

I noticed a couple puffs off white smoke a few days ago. It hasn't been consistent and I've been trying to convince myself its just condensation in the muffler. Any ideas on what would be fine when you start up but cause problems once the jeep has been at operating temperature for some time?

Now before I get called out for being cheap, I know I should just do a complete tune up. I don't have money today to do a complete tuneup, but I can say, pick up a distributor cap. And if I can fix it today, I can go wheeling with a bunch of my jeep friends. Oh, and I also know that you end up putting a bunch of new stuff into jeeps and the problem gets fixed by the very last simple thing you do. any advice?

 

Could you be creating a vacuum in the fuel system? Do you have a venting gas cap, or is the system vented? Try loosening the cap when it's acting bad and see if you get any suction or if it smoothes out. It may be as simple as buying a new venting gas cap.

I would think if it was electrical or head gasket related, you would see the problems from the beginning.

 

I'm not sure if the 74 has a points and condenser system but if it does then I would suspect the condenser is breaking down when it gets warm. For the few dollars it cost to get one it would be worth it to try a replacement.
WW

 

Just an update...not rocket science or anything but a new condensor, distributor cap and points set adjustment and shes purring like a dream. Just my luck, I ripped two holes in my radiator using a ratchet on my crankshaft for the points set adjustment. That JB weld on a stick works GOOOOD!!

Oh yea, ditched going wheeling to go to the biggest car show of the year. Didn't see many cars, ended up spending the day gawking at the 57 DJ