1999 4.0 Sohc codes P1151 P1131 P0171 P0174

[wzurell]

Having very hard cold starts, but after the engine warms, it works great. Recently replaced plugs, MAF, fuel filter, cleaned throttle body. Anyone have any ideas? This is on a 1999 Explorer XLT, 4.0 SOHC, 90,000 miles

 

[drdoom]

I would wager a wild guess intake manifold gaskets. Or maybe a pcv elbow.