HI, Took the 420 to a wedding this afternoon; bought a tank of super about 20 miles from home; about 20 miles later, the engine cut out or stumbled for a second as I turned a corner. 10-15 miles later, it bogged and died on the road. It started right up, idled perfectly and drove fine, then about 10 miles later, same thing. I made it to Natchez, and it ran fine about the last 15 miles. I started home, and about 20 miles into the return, it started cutting out and stalling again. I could usually back completely off the accelerator for a few secouds, and it would pick up and run fine for a few miles. Sometimes it would quit completely, at which time I went to neutral, turned the key off for a few seconds while coasting, then it would restart and go on. Toward the end of the return trip, I stopped for more fuel, thinking it might help. Problem seemed to get much worse, finally it would run smoothly and pull for a few seconds to a minute or so at a time, then stall. It would always restart and run fine for a short while. I called the flatbed and made the last 10 miles in shame, thankfully it was at least dark. What do you think? Bad gas? Fuel filter? Fuel injection problem? Ignition? I bought the car not running in Dec 2003, replaced both fuel pumps and the filter, and it ran fine then. Have put about 7000 miles on it since then, I did change the timing chain and guides and tensioner a couple of years ago; had 7 degrees stretch in the chain, but guides looked OK and the tensioner seemed good but I replaced it with an OEM part.