Driving the car yesterday, it felt like I had fueling issues. Stumbling off idle was bad enough, the surging worse
Got it to where it would run at least vaguely right, then took off down the A38 for an exploratory.
The engine sort-of laid over when I shifted to third, so I backed out of it and then gradually re-opened the taps. Wound it up to ~65mph in third then went for top. Wound it up some more STAYING UNDER THE SPEED LIMIT AT ALL TIMES OFFICER *looks around shiftily*. Sat cruising at somewhere between full and flank speed. Came off at Branston, it seemed to be running pretty okay at that point so I went to the supermarket for provisions. There was a fun moment there - I get back to the car, and a chap comes bounding over. "I haven't seen one of these in real life before!"
Told him about the project, he had an admiring look-around, then went on his way. I fired back up, figuring that if it stumbled at all as I came out of the car park that I'd head back through town instead of risking the A38. Pulled out, seemed fine. Drove down to the A38 island, seemed perfectly fine. Drove around to the A38 exit, fine. Accelerated to join the A38 and whoosh - she took off like there had never been anything wrong. Banged through the gears up into top, full speed ahead, cruising at warp factor 1.
I figure I had fuel starvation going on. Stumbling off idle could easily be a fuel supply issue. Running into a lean condition would also explain the surging. Or maybe there was just some crud in the carb and the run at speed cleared it up. Gonna pull the fuel filter out and replace it anyway since I have replacements.