1994 3.1

In the last month or so my engine seems to be running a little rougher. My gas mileage has dropped about 13% or so (from about 20.5 @ gal to about 18 @ gal) although I live in AZ and have been running the A/C much, much more than even a month or two ago.

I haven't gotten any "Service Engine Now" codes or lights and in "Park" the engine seems to run smooth enough. There does seem to be some decrease in acceleration power. It isn't using oil or water. In late June I had a new A/C compressor put on and in early July a new starter and alternator.

The motor mounts are bad and I am wondering if the engine vibration is being transmitted more directly to the frame although this wouldn 't explain any loss in acceleration power.

Any ideas?