Check the crankcase vent system. don't know what yours has, could be PCV or CCV. On mine there is no PCV valve, a line from the front of the valve cover runs to an orifice in the intake manifold, the second line runs to rear of valve cover to the air cleaner to supply fresh air....either system could be blocked..
2013 WRANGLER SPORT 2 DR., V-6 ,AUTO,HARD TOP
)1994 Jeep Wrangler 2.5L, Bestop top
/w steel half door and slider windows
5 speed, 2.5" lift, 31" tires,rack lights