Error code P1151 after replacing intake manifold

This is a good link http://www.obd-codes.com/trouble_codes/ford/p1151.php I think I read a note somewhere about bad electrical connection/corrosion at the O2 sensor connection due to water/salt from the road on the F150. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online

P1151 = lack of HO2S21 switch (HO2S=heated oxygen sensor). The problem is that a P1151 can either be the result of a true overriding lean condition or it may be a bad sensor signal that's giving a false reading. Or you can try to replaced the designated o2 sensor. Hope this can help you. Best regards.