Gas Milage in the can

New to the forums. We have a 1994 grand marquis V8 over head cam. It's a 22 gallon tank and until recently was pretty good gas mileage for a V8. The car has around 1100,000 miles on it and when it was services at 100,000 the mechanic said it will last another 100 if we treat her good. About a month ago it started vibrating when you accelerate and you can kinda hear it a lttle bit too. Anyway it feels like your driving on an old stone road when you are accelerating even when you are on flat pavement .I put some fuel injector cleaner in it a couple weeks ago with no real change. My wife hit the trip meter when she filled up and only got 181 miles for the whole tank. Given she does do a lot of city driving, but i remember it being closer to 300 a tank when i was driving it throughout Philadelphia. So my question is does anybody have an idea of what the problem may be? And an ball park about how expensive the solution will be to fix it. Thanks a lot

WHen was the last time the plugs and wires were replaced? Sounds like you may just need a tune up.

New to the forums. We have a 1994 grand marquis V8 over head cam.
The car has around 1100,000 miles on it and when it was services at 100,000 the mechanic said it will last another 100 if we treat her good. About a month ago it started vibrating when you accelerate and you can kinda hear it a lttle bit too. Anyway it feels like your driving on an old stone road when you are accelerating even when you are on flat pavement . Thanks a lot

Poor gas mileage can be caused by many things.
Especially on a vehicle with "1100,000 miles on it". :confused:

Take for instance the Serpentine idler pulley & Serpentine tensioner.
Worn bearings in those parts will cause more drag on the engine,
resulting in lower fuel economy.

More possible suspects include but are not limited to, spark plugs, spark plug wires, coil packs, air intake temp sensor,
coolant temp sensor, mass air flow sensor, oxygen sensor, pcv valve, egr valve, dpfe sensor, vacuum leaks, ect.

The "vibrating when you accelerate" & "feels like your driving on an old stone road"
sounds like "torque converter shudder" or possibly clogged EGR ports.
Ask your mechanic to check for TSB's (technical service bulletins)
& pull any DTCs (Diagnostic Trouble Codes) from the OBD (On Board Diagnostic) port.

Thank you very informative info!! Obviously i meant 110,000 miles too:) not over a million!! Do you have an idea about how much something like that would run to have him "check for TSB's (technical service bulletins)
& pull any DTCs (Diagnostic Trouble Codes) from the OBD (On Board Diagnostic) port. " Thanks again for the help. Am i able to give you points for a great answer or something? I know some forums have that but i cant see a place to mark that you solved my question. Thank you

We don't have a points system. But you just gave him thye best thing you could. We all like to be recognized and you ceretainly did that for
JR Tigerstar. All that is missing is the fix poast that is sure to follow after you go to your repair shop. Thank you for aknowledging the time he has put in to answer your question. Good job JR. And thank you lb one4truth for using the forum.

The wash board feeling while accelerating is the torque converter,it is a common problem with these cars.It will need to be replaced,there is a tech. service bulletin on it if you care to search Ford TSB's.But on a 15 year old car finding the TSB won't really do you any good except to tell you what might actually be wrong with it
Start looking here
http://www.mycarstats.com/auto_TSBs/FORD_TSBs.asp

Look for transmission supply houses they rebuild them. It would be a lot cheaper than a new one. Flush all cooling lines and drop the pan and look for trash when you pull it. These are easy put it on jack stands place a floor jack under it and I use a short piece of 2x10 on the jack.