My wife is telling me that the gas pedal on her 90 560 sel sometimes feels like the gas pedal is pushing back up towards her foot and not letting her push down. I can not drive so I cant tell you what I feel just what she can tell me. I am thinking air filter and or fuel injectors. Cleaned K&N air filter treating injectors with sea foam as she drives now. Will replace fuel filters, if someone can tell me how many and where are they located. had car less than a year. put 8,000 miles on her so far ( The 560 not the wife) any other ideas or areas I should check?