Landcruiser LC4, HELP required

Hello everyone. I'm new to this site so bare with me please. 

I bought a 2003 landcruiser lc4 1kd around 1month ago its been stood for 2yrs it had engine issues where it would cut of randomly when driving. So my mechanic drained the tank cleaned the filter on there replaced the fuel lines and changed the SCV valves and gave it a full service and lo behold the car started behaving with no issues. So I drove it 240miles on the motorway with no issues only issue it has was that it would take around 30secs of cranking multiple times before it would start but if the car was left overnight it would start immediately the next day but then if you turned it off and tried starting it again it would just keep cranking like before. So after the 240mile trip the next day its starting to go into limp mode with the fuel line malfunction code and the fuel temperature sensor bank A code and randomly cutting out as soon as it goes up a hill or try to set off from a junction engine light comes on immediately and cuts out but when you turn it off and then back on its fine except for 30secs later. My mechanic had a look at it and seems to believe it's the fuel pump on the engine and its getting air in the fuel system from somewhere. Is there any advice that you guys could give me please.

Tia

Try to replace the fuel filter housing. 
there must be a leak somewhere in the pipes? Did u change the complete fuel line?