My 96 4.0 Grand Cherokee w/170,000 miles started this ruff/low idle after a cold weather start (-18/-37wc). After it final started (small burst of starting fluid) it ran well at high idle but as soon as it warmed up it started to spit and sputter on the low idle. It will run with giving it gas but drops off as soon as you lift. Weather is back to normal so i changed out the MAP and Idle Air control valve and ran a can of carb cleaner thru with engine off and new parts not installed yet. No change! the only thing that i notice now is a thumping noise at the Vapor Canister Purge Solenoid that starts and coincides with it idling down and running ruff. Any ideas? and yes i have checked for vac leaks and found none. Also noticed on last test drive that it seamed to want to lunge but with no sort of rpm jump.
Update 1/14/14: Check engine light came on with code-PO171 (Bank 1 system too lean). Changing PCV valves and installing new breather lines to air intake box and manifold. Also changing fuel filter.
Update 1/14/14: Check engine light came on with code-PO171 (Bank 1 system too lean). Changing PCV valves and installing new breather lines to air intake box and manifold. Also changing fuel filter.
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