OK, my tank was nearly empty (light was on for about 5 miles) so at lunch time I got a bottle of Heet and threw it in there, then added 5 gallons of gas. The Heet bottle says it treats up to 10 gallons, so I should be OK. On the way back to the office, it still did the occasional jerk, but I don't expect the Heet to work immediately (if at all, depending on the cause). I'll drive this tank empty and report back if there is any improvement.

Interestingly, I had to go to WalMart to get the Heet, since the gas station was out of it. But the station attendant told me that if I couldn't find Heet, I could just use a capful of isopropyl alcohol and it would be just as good. Anyone know if that's accurate?

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280