Fuel Injection problems of the 2001 Lincoln Navigator

Accelerator pedal becomes hard to depress whenever temperature is below fifteen degrees f for an extended period. Once depressed, idle does not return. Engine rpm stays elevated, dropping only when gears change, then building back up to "stiuck" rpm. When placed in neutral, engine revolutions increase to almost 5000 rpm; placing vehicle in drive causes rpm to drop to approximately 2200, which is consistent with 70 mph in drive. Vehicle cannot be stopped unless gearshift is placed in neutral or ignition turned off. It would appear that conditon relieves after about twenty minutes of driving, consistent with some internal component warming sufficiently to relieve a cold-originated contraction apparently causing binding. Condition returns randomly at somewhat higher temperatures at speed, almost as though responding to wind chill cold. Dealer obeserved conditon in two-day obervation, did not cure probelm, yet released vehicle in unsafe condition. No followup following week; reported to Lincoln customer care, but complaint ignored; no action taken. "we'll investigate" three weeks now.