I have a 2003 Mazda MPV with just over 36K miles on it. I have the extended warantee but I am stationed on an island in the Azores so it doesnt do me much good here.

The first time I noticed the problem was backing up. It was real jerky and I suspected the transmission. I checked the fluid and it was approx 1/2 guart low. I topped it off and the problem still remained.

I even tried dry gas just in case I had a little water in the tank but that didnt help either.

I read on this site that the rear coils sometimes go bad due to excessive heat. I talked to local mechanic and he suspected the same thing.

The problem is getting worse but only in gear. If it is in park or neutral it doesnt seem to skip at all. The heavier the load you put on it the worse it gets (like going up a steep hill)

Can anyone tell me how to troubleshoot this and verify if it is the problem before I spend $200 in parts and tear apartmy wifesfairly new vehicle?

Also are there step by step instructions anywhere for changing the rear coils & plugs?

 

It does sound like a severe engine missfire due most likely to failing coil(s). The problem you are going to run into is to detemine which one(s). Is you CEL on?? It very rarely is with an MPV missfire but have seen it happen. The Mazda diagnostic computer at dealer can actually record which cylinders are missfiring and how may times to a fairly accurate degree in a real time driving test. I would not however count on the rear coils being the faulty ones. Out of the 200 or so that I have replaced for varying degrees of engine miss, the fronts failing are close to the same ratio that rear ones do. Coil primary and secondary resistance readings typically always looksnormal so that kind of testing will not help much either. If you only have 36K miles on it then you should still even be under the factory OE warranty of 4 years/50,000 miles. How far away is the closest Mazda dealer to you? Before undertaking this task by yourself you might give Mazda customer assistance a call at 1-800-222-5500 and explain the situation. They will probably will be even more responsive if you mention that the missfire is very severe and you are concerned about engine or catalytic converter damage. Mazda does have a roadside assistance program that will allow your engine to be towed or otherwise transported to the nearest Mazda dealer. Do not know how this would fly in a foreign country such as the Azores but just might be worth a phone call to find out. Roadside assistance is 1-800-866-1998. They might even authorize an independent repair facility to make the repairs needed and would then reimburse you for the cost out of pocket to you.
It is not your fault that you got stationed somewhere without a Mazda dealer now is it.