So I changed my exhaust manifold because it was cracked and now after i changed it my jeep gets worse mpg a very noticeable difference I already changed plugs wires dist cap and rotor coil. I am running out of ideas of what it could be it's 99 4.0 i6 87000 miles

 

It could be your right foot. Once you changed your exhaust manifold you probably got better power and now your using it.

 

Wild-*** guess here, and somebody will surely tell me if I'm off base, but did you reset your ECM to factory defaults after putting the new manifold on? New O2 sensors, too?

 

I already thought maybe I was punching it to much so I started driving like a old man buy that didn't help

No I didn't reset it don't you just unhook the battery for 15 min. I didn't change the o2 sensors how do I tell if they are bad?

 

Just change the O2 sensors.