5.4 Engine stalls, lacks power
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5.4 Engine stalls, lacks power
Been having two different problems with my 2002 Navigator. Occassional rough idle and lack of power, also completely stalled once. Was throwing codes 171 and 174, replaced bad elbow on back of intake plenum from PCV, codes kept coming back, but rough idel fixed. Also replaced fuel filter, air filter, refilled fuel twice with quality 92 octance and injector cleaner. Finally took to dealership who smoked engine and found another leaking hose on intake plenum. That fixed the codes, but still lacked power under accel. Mechanic checked fuel injector flow and leak down: found to be OK. Then he replaced the K&N air filter with an factory one, still no change. Then he cleaned the MAF (which he thought had oil from the K&N on it) and engine ran great. 30 minutes after I picked it up it began to lack power and stalled. Started up fine and took back to dealer, who road tested for 30 minutes with no problem. No codes set. He thinks it may be oil from when the K&N was installed possibly in the throttle body getting released into the intake. They seam stumped, but are still checking. Anyone have any other ideas? Anyone ever had problems with K&N in the 5.4?
