error code P2187 P2189

[jhy311]

hi, everyone, greetings from Texas.
mine is 03 4.4i
SES light turned on one week ago when I just finished pumping gas. I originally thought it was caused by the cap. after one week, the light's still on, but everything else seems normal. then had the codes checked this morning, two showed up P2189 P2187.
it says "system too lean at idle speed bank 1, bank 2". I did nothing but went ahead erased the codes.

after the codes were erased, problems started. the engine quickly shut down after I turn it on. It appeared to have very low idle speed. I had to put the gas pad hard to keep the engine running. and at idel, the engine shakes alot, and the idel speed is low and unstable.

can anyone give me some clue. how come the engine runs well before I erased the error codes, but run terribly afterwards. I hope the engine can come back to normal after running a while.

thanks for your attention.

Eric