My 1994 Voyager (3.0/3spd) has recently felt down on power and my mileage has dropped tremendously from mid 20s down to 14mpg.

It seems to be running normal and has no CEL.

It's a 3.0 with some work done, ported/polished/milled heads, ported polished plenum, 52mm TB, intake, full 2.5" exhaust.

I changed the fuel filter last weekend, which helped the power some, but it still feels down and still gets crap mileage.

Wondering where I should start now?

 

Should also note:
Plugs, wires, cap, rotor, and O2 were all replaced about 10k ago.

 

Anyone got anything on this?