C280 ck eng lgt P0170 and P0173

[louietwo]

Help!!! 1999 C280 with 36K miles ck eng lgt on ..displays codes P0170 and P0173.."lean fuel trim"....replaced gas filter and replaced both O2 sensors...still same problem...replaced gas cap...still same problem..replaced air filter..same problem...cleaned MAF sensor...still same problem....ck lgt was turned off with ob11 after each attempt to resolve problem but ck lgt returns!...funny thing is the engine does not exhibit any run problems and runs great.....help!!