OK. A couple of other things to check, and then I'll shut up.

Be sure the oxygen sensor is working and that the on-off ratio is reasonable, like 45-55%.

Check to see if the pressure dampener is leaking and gas is getting sucked in through the vacuum line

There is one, maybe two vacuum fittings on the WUR. Be sure that both hold vacuum on the WUR side.

Be sure the o-ring on the FD is good and not leaking.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe