Mitsubishi: 1999 Galant issues, mitsubishi galant, cruise control

Question
Hello.  I have a 1999 Mitsubishi Galant ES 4-cyl.

Hopefully I don't give you too much information.

I purchased the car used in late 2001 from a dealership.  Previously it had been a rental.  The car had run excellent except for a minor "rattle" (slight vibration of the car is noticeable)  of sorts coming from the front, passenger-side wheel area which has been there all along and only occurs when gently slowing from a fast speed (i.e. 60 mph) without pressing the brake.  It seems to cause a slight uneven wear on the tires, and alignment jobs haven't seemed to remedy it.  But it hasn't bothered me much at all (and is not the reason for my posting - and I mention it only for just-in-case).

After the mileage passed 100,000 the service centers kept encouraging me to get the timing belt replaced, and so in June I finally gave in, and they replaced all of the belts, including the timing belt, and they also replaced the water pump - since Mitsubishi recommends that.

Immediately after getting the car back from the shop I noticed (even as soon as the moment that I started the car to drive it away) that the engine ran noticeably more rough than it had before, including a slight tendency for the engine to race a bit more than it did before on startup and when aggressively accelerating (forcing a downshift).  I hear more noises from the engine continually now, including a kind of "ticking" that before could only be heard when the hood was up.  And, the worst part (and the part that concerns me and is the reason for my posting now) is that if I am on the highway at about 60 mph and if I gently ease off of the accelerator, especially when going downhill, the car will "shudder" like the transmission is sticking or maybe the engine is misfiring or something.  If I change the depression of the accelerator (up or down) the shuddering will stop.  The shuddering also occurs when in cruise, although the cruise control seems to compensate for it more quickly than I normally can.

I have taken the car back to the same shop twice now and had them recheck their work, and I've driven them around to demonstrate the problems to them, and they say that they didn't cause the problem and that they don't know immediately what the problem is and that if I want them to investigate it further it will cost me.  I am not excited to have them work on the car again.  So I've just been tolerating the problems for a few months now... although the problems seem to be worsening (beoming more noticeable and frequent).

I have replaced the spark plug wires (just for good measure, as I guessed that may be a potential cause) and I have looked into the engine and around cabling in the dark (garage at night with lights off) and have seen no electrical arcing or any lighting/sparking of any kind in the engine.  I have changed the oil and filter.  I have changed the air filter.  I have cleaned the PCV valve.  I have checked the automatic transmission fluid.

Last week my wife was driving the car out of a parking lot at a low, low speed when it shuddered very hard - as if the engine were dying or as if she had hit something - the "Service Engine" light came on immediately, but the car kept running and the shuddering stopped, and she was able to drive the car home.  In fact, as soon as the shudder stopped (which was very brief, momentary only) the car began running much more smoothly than it had since I got the car back from the shop.

I took the car to a different shop to have the "Service Engine" light diagnosed.  The diagnostic code was DTC P1751 which apparently indicates something (although somewhat vague) with the transmission occurred.  They cleared the indicator light and the light has not returned, although the engine has begun to run a little more rough now in the days since.  That shop was unable to see any obvious problems that would lead them to understand why the light went on or why things would be running the way that they are.

I would really like to get the problem fixed, and I don't want to one day have the transmission fail when I'm 90 miles from home.

Do you have any idea as to what the problem could be?  I wouldn't mind spending $1000 to get the transmission fixed ahead of time if that will solve the problems.

Answer
Are you a columnist? Sheesh! LOL Ok, first, just to pacify me, replace the plug wires with genuine Nissan wires, non of this spagetti they sell at your 5 and dime. What your discribing to me is a misfire. The plug wires could also be crossed(likely). If you find this is the case then don't buy the wires! The shop you took it to seems a little bit on the schister side if they want to charge you to look at something they possibly caused. BBB if I were you. Immediately.

Ok, lets talk about the code P1751. This is the automatic transmission control relay acting up. Located under the hood in the power distribution box. The lid of the box should tell you which one it is. They run like 20 bucks, might be worth getting a new one. I know one played hell with me in my boat.

Let me know how this does and if we need to, we will plug at it some more. I hope those guys didn't set the timing off a tooth...