I have a 98 f-150, it idels fine in park when in gear it drops to 500 ecceleration is slugish, when i hit 55 or 60 my speed levels off if i give a little more throtle it slows down, if i drop it to the floor rpm goes up to about 4500 and ground speed drops. If i play with the throtle it will get up to 70 and go through the same thing again. I have 2 codes P1131=lack of HO2S11 switch sense lean and P1151 same thing but bank 2. Any one have any idea?