Q: Car had codes for two misses in coils. Replaced all but two spark plugs and coils. However my car loses power going up hill.

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My car threw codes for 2 misses in the coils. Engine shakes when I accelerate over 35mph. I've replaced 4 of the 6 coils as well as the spark plugs. I'm also have trouble going up hill and lose power going up hill. My car didn't throw any other codes and this all is a very sudden act up.

My car has 337872 miles.
My car has an automatic transmission.

There are a number of things that can cause a misfire code besides an ignition coil. There could be air leaks, injector problems, or even a mechanical malfunction in the engine. But if you are not seeing a Check engine light anymore, you may have solved at least part of the problem. Loss of power can also be caused by a number of things but if you have been driving for a long time with a misfire, it may be that you melted the catalyst and there is now a restriction in the exhaust. The truth is, at over 300 thousand miles it could be just about anything. Your best move would be to have this thing checked out professionally before spending any more money on parts. Contact Your Mechanic to have a technician come out to your home or office to check out your Highlander and let you know what it is going to take to fix it.

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