A There are a lot of things that could be causing problem #1. The first thing that you should do is have a qualified mechanic take a look with a scanning tool and see if there are any trouble codes. These stored trouble codes can offer a world of information in solving the problem. I would just be guessing in anything that I say, but here are my somewhat educated guesses anyway.

The first thing I would look for—and it will only cost you a bit of time to search out—is a disconnected or leaking vacuum hose. Tug, pull, and check out each and every hose you can find. A lot more accurate way would be to use a Rotunda Vacutec 522 smoke leak detector machine (or something similar). But then again, you don't have access to one, so use your eyes.

The idle air control (IAC) valve assembly controls engine idle speed and provides a dash pot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The power control module (PCM) determines the desired idle speed or bypass air, and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the valve to control the amount of bypassed air. The PCM monitors engine rpm, and increases or decreases the IAC duty cycle in order to achieve the desired rpm. The OE part number is YL3Z-9F715AA, and the cost is about $120.

Ford used at least two different manufacturers of this item. The valve is not repairable or cleanable. I am not saying that this is the problem, but just one of the things that could cause the problem.

As to problem # 2: Always use the transmis sion fluid that is recommended by the vehicle manufacturer. Any other fluid may not be compatible with the internal components, especially the clutch plate material. Yes, automatic transmissions have clutches that engage and disengage between gear changes and have certain friction requirements. Using the wrong fluid— and even transmission additives—that may or may not be compatible with even the proper fluid can cause all sorts of shifting problems, and very possibly the ones you're experiencing. You need to read the labeling on the fluid package as it will state what requirements that it meets, such as if it does meet the Mercon V requirements.

While there are quite a few additives available for engine oil, transmission fluid, and gear lube, it is hard to say if they really add any real benefit. The only way to really find out would


be to have a testing lab do some extensive (and expensive) tests with each particular brand of lubricant used, as each has a slightly different additive package. I suggest that you drain the present fluid out of your transmission and start over again. Unfortunately, what is in the torque converter will not drain out, so you may have to make several transmission fluid changes after driving the vehicle a few miles to remove the majority of the "wrong" fluid.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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