93 F150 4.9 ,runs ok ,but check engine light on with codes above . She stummbles off idle and sometimes stalls.Mileage also down. EGR works with vaccume applied.Is there a test for EVP / EGR position valve sensor? 116 = engine coolant out of self test, and 636 = tranny operating temp sensor out of self test range also. Any thoughts on these tests before parts swapping?thanks