Intermitent Surging
 

Made a road trip this weekend through the AZ mountains to Willcox. On the way I notice the car "surging" at constant throttle. Not a lot but enough to be noticeable and annoying. Got a bit worse on up hills with constant throttle. Seemed to have full power when asked but the "surging" was constant. Got to lunch when I got back on the road making my way down AZ 191 surging was gone. Stopped to check in to the hotel and on the run to the track, surging was back. Next trips were all with a cold car (34 in Willcox in the morning who knew) with one or two showing the same tendency.

Sunday was an interstate blast back to the Phoenix metro. Running between 3400 and 3800 the entire way and no surging. Car ran like a train. Had plenty of power when needed and got much better gas mileage to boot. Did over 220miles with just less than 1/2 tank showing. Run on Friday with the surging got me barely 150 miles with basically the same fuel showing.

Thought bad gas, but have filled up at reputable stations, fuel filter is clean. Thoughts?

Sorry motor is a bone stock 3.2 in a '69 chassis