I got in the car yesterday and it started great. I drove for about 15 miles with no problem, but then the speed and power started to increase and decrease as though I was moving the pedal, but I wasn't. I slowed down below 60 mph and the problem went away. It then came back and I had to slow down below 45 mph to get it to stop again. At a traffic light the engine died and I restarted and drove 4 miles home without problem. Today It started again so I tried to restart the engine but the symptoms remained. Does anybody have an idea of what could be wrong?

Thanks

John

 

vacuum leak

 

Perhaps You have a problem with your carburetor iceing over or if your carb has a automatic choke it may not be running properly.
My 1973 cabrio has a 1971 engine, it's carb ices up depending on the the weather, but the auto choke allways tries to cut the engine once just started. But it's never happened for no more than 2 miles at the begining, it's never been anywere near 15 miles when the problem began. So your problem may be a bit more serious.

 

Tighten up your auto Idle Adjuster. Located to left of carburator, should have a wire going to it. Need a flatter open end (I think 13mm) wrench to tighten it. Used to happed all the time to mt 73 bug. If not you have a Vacuum leak or hole in Fuel line leading to Carb, sucking air!