My math tells me that if the current injectors are 18 years old, then they were renewed in 1986, which means that the original set lasted 14 years.

Not being one to spend another's money wildly, I would have to say that replacing the injectors would be a good investment especially if you are going to keep the car. New injectors made a big difference to my 380SL. And yes, you should replace the seals while you're in there.

Good luck!

__________________
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