Monterey shuddering/jerking at slow sppeds

Hi, Our 05 Monterey has this problem at around 45-50mph speeds. At this speed when we step on gas the we feel the vibrations of slow jerking like misfiring and some rough driving experience. This does not occur when cruising around 60/70mph. Biut if you have to brake and the speed drops below 45, then while accelerating the above problem is experienced. The car also does not accelerate fast enough. The car has around 110k on it. What kind of maintenance does this need? Is it very serious and need repairs right away? It was not a daily driver car, but now has become one (30 miles) for work. Thanks,

Because of the speed that was mentioned, I think it is possible that the problem lies in the transmission’s torque converter lockup mechanism. If you have never had the trans fluid and filter changed, it is very much overdue, and performing that service may just relieve the symptoms.

As to the slow acceleration, this is most likely the result of other types of lax maintenance, such as failure to change the spark plugs, plug wires, and air filter. It is even possible that a partially-clogged fuel filter is contributing to the acceleration problem.

You need to compare all of your maintenance invoices to Ford’s maintenance schedule in order to see what procedures you may have skipped over the past few years.

Thanks for the quick reply. We have not done any trans fluid change untill now. We bought this vehicle used around 60/70k on it and dont know if earlier owner did that. We did oil change a week back He was recommending fuel injection system cleaning ($100). Will this help?
I was also wondering about spark plugs. It looks not so easy task (access wise) to do at home!. It’s good to know that it may not be a major problem. Thanks again.

Cleaning the injectors might help, but you can do that yourself by simply adding a bottle of Chevron’s Techron to your tank and then filling the tank and driving until it is almost empty.

Regarding the spark plugs, trans fluid, and all of the other maintenance items, unless you have hard copies of maintenance invoices to verify that they were done, you have to assume that none of the required maintenance has been done. Unfortunately, that is part of buying a used car that didn’t come with maintenance records.

In addition to the other procedures that I already mentioned, unless you can verify that the coolant/antifreeze and the brake fluid have been changed w/in the past 3 years or so, those procedures are also overdue.

I would strongly recommend having the transmission pan dropped, filter changed and then refill with the proper fluid to deal with the symptoms described. But if the car’s maintenance has been lacking it needs a great deal of attention.

We checked with our mechanic (firestone) and he did not find any issue in his test drive, but we still feel the slow jerking while accelerating. The trans fluid looks very clean, the dip stick comes out very clean, light red color. This morning did not feel that much vibrations, but two days back it was rough. Don;t understand what could be the problem. Don’t know if it could be tires, they are at 4, but don’t feel vibrations at high speed. The gas tank is almost empty and I am going to try the chevron techron mentioned above. I have got the ‘complete system cleaner’ which looks slightly different from the concentrate plus, is it okay to use it? Since this is a minivan with bigger tank I got the bigger 20oz bottle. Let me know. Thanks,

VDC driver stole the words right out of my mouth by suspecting the Torque Convertor lockup issue…if a convertor wont unlock…you will see exactly this issue.

Rod Knox is also on the correct path as well… Definitely drop the tranny pan change the fluid and filter…see what you get.

Dont do ANY other repairs until the transmission is sorted out and Happy again…the issue more than likely lies with the transmission.


You might inspect the intake tract between the MAF sensor and the throttle body. The slightest of air leaks in this area can cause a symptom like this at those speeds

We recently (April) replaced the Fuel rail pressure sensor when check engine light came on. Anything to do with that? Is it installed in same area?