check engine light

After road test rebuilt engine i am getting codes PO136... P1131 ..P1000. New 02s.. no vacuum/exhaust leaks... it does indicate a lean condition, am i right here... engine runs perfect so it seems, the PO1000 drive cycle not complete... the only thing that i think could be the fuel pressure or injectors, anyone like to add comment.. this is a California 1998 ranger 2.5 the PO did gut out the front cat, rear one intact

Got brand new cat pipe only used to start owners truck $300 sorted out check engine light problem but was left with PO 171 ... then it stopped and cleared P0 1000 got the cali smog done..... and yesterday 171 came back after putting seven gall of gas in tank ...dam it did that before when i filled tank ??? ???? Crap.. GAS cap thats my problem..