Gas Mileage

If you are in an area that mandates MTBE in the gasoline (for air quality) this could be the cause. If I use fuel that contains MTBE during the cold winter months I see as much as a 20% drop in mileage.

Of course other things to look at would be PCV Valve, O2 sensor, dirty air filter and such.

Have you pulled the codes to see if they reveal anything?

Any codes set? If not, my first guess would be O2 sensor, but it could be any number of things. My Chevy truck had this problem and it never set a code. Turned out it was the coolant temperature sensor and the engine thought it was cold all of the time and provided a rich mixture as during a cold start.

Matt

This happened on my 89 Acclaim 3.0L - turned out to be a broken thermostat - code 17 was set (staying in open loop because the engine temp didn't rise within a certain period of time). Easy to put in a new one. Good luck.

bob

When was the last time it had a good tune up ? My 88 3.0 New Yorker does better with fresh filters and plugs, and rotor and cap. Also check for EGR issues and open vac lines to sensors ? Is your tranny slipping? Carrying alot of dead weight all the time ?

Just places to start

Steve