Car will startjust fine but on two mornings in the past month l had to keep my foot on the gas pedal for a few minutes in order for it to stay crunk. What is wrong? Tune up? Bad Gas? Or what?

your gas pipe is probley cloged or something

To stay crunk? This is not a vehicle for crunkin' :-) (or at least the ones l have ever seen)

Ok with that out the way, I'd say you are not getting enough gasoline pressure to the engine.. if it does it again, stop the engine, cycle the key on and off about 3 times without starting them start it.. problem goes away? Need to find out why no fuel pressure.. fuel filter, but probably trash in the fuel line or my vote for a fuel pump..

Your idle control sol. is not working properly.

Simple fix, The IAC valve is sticking, It is located under that plastic cover on top of the motor. Seen this many many times. The easiest way to know is to do this. Take cover off when it acts up & wo not run. TAP it with a hammer ( l know this does not sound good but it wo not hurt it) with the key in the run position & if it starts & idles fine then the IAC needs replacing. The IAC is a valve that controls the air flow into the engine at idle. It is a shinny/ chrome valve that bolts to the upper intake & on that model will have 2 wires & a hose about 1 inch going into it. The valves will stick causing it to do that. Go to a dealer & get one, they have been redesigned not to stick any more.

l am very formula with the engine setup and l do not know where the JOSH S is talking about under a plastic cover. If it has only happened twice in a month you will just have to wait its not a tuneup or bad gas it would happen a lot more then a couple of times. You should note if you have your cooling/heating system turned on when it happens if it is related to your A/C you should be able to just turn off your heating/cooling system and see if that makes a difference.

miked is a not very familer with that set up obviusly anyone that has spent ant time at all woring on a ford 4.6 will know about the iac josh is right go to your dealer and tell parts guy u need a iac ill bet they have it in stock if they dont they r sold out l put at least 2 on a month

The Mercury Grand Marquis does not get good EPA gas mileage highway or city.