f150 bank system code issues

I Have A 1996 F150 With A Fault Code Of P0171 And 0174. These Codes Are For A 8 Cyl Truck But The Problem Is I Have A 6 Cyl!!! Whats The Cure!!! Could The Computer In The Truck Have Been Replaced With An Incorrect Type? Where Is The Computer Located And How Would I Knowif It Is The Correct Type? Help Please

P0171 is the code for bank No. 1 running lean, and code P0174 is the code for bank No. 2 running lean. regardless of number of cylinders.

Clean the MAF and check for a vacuum leak downstream of the MAF. if neither or those are the problem, check fuel filter and/or fuel pressure.