One problem related to vehicle shudder has been reported for the 2004 Mercury Monterey. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Mercury Monterey based on all problems reported for the 2004 Monterey.
First occurrence at 43k miles. Traveling at about 40 mph on main road when engine speed increased and vehicle drifted powerless to the side of the road. Examination by Ford advised bad trans, first time they'd seen the problem. Not covered under extended warranty. Estimated repair - $3500. Took vehicle to aamco - initial estimate $2000 but once opened up advised that full rebuild was required due to extensive metal fragment penetration throughout system. Cost - $3500. On 6/2/11 was traveling at 35mph on local road. On accelerating after a right turn, the entire vehicle shuddered and the engine speed increased. Vehicle drifted powerless to the side of the road again - roughly 40k miles on rebuilt transmission (83k total vehicle miles). In checking transmission fluid level, there appeared to be water in the system. Towed to Ford dealer, advised that this was not a normal occurrence and they didn't see if often. Advised that, based on age and mileage of vehicle, transmission should just be replaced. Estimated cost - $3500. Vehicle is now on second transmission at less than 85k miles.