Probably a coil, but getting the codes read would be the first step. A flashing CEL indicates multiple misfire, but you need to know which cylinders are the problem.

I could also be a fuel pump problem, not delivering enough fuel when going up hill. But, then on the 'flat' the misfire should have gone away.

As for a bad coil or two, once you have the codes read, swap the coil to a 'good' cylinder and its corresponding coil to the bad cylinder. If the code moves to the 'good' cylinder, you know the coil died.

I don't think these could be the original coils, not at 195K. Check the WWW for best bargains/value. Dealers are a bit expensive.
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Keeping it running is better than buying new