How will you know when to replace out the intake manifold gaskets

2001 dodge dakota pick up will not stay running . engine starts but stops immediately. engine had over

heated. bad radiator. Put pick up on diagnostic. Had to replace out the , injector (all)

Throttie sensor, intake air temp. sensor, Engine coolant temp. sensor,the MAP sensor,

ldle Air control valve. spark plug, All the lgnition coil. And the Radiator. Put it back on the diagnostic, all good no more trouble codes. Even check all the vacuum hoses. But

it will not stay running. WHAT DID I MISS ? ? ?