Fuel system problem

my car is an 01/w a3.5l after the standard fuel system maintnance/tuneups computer resets it is dumping my fuel in town. rural driving is 24 mls per gl, hwy is 27 to 28 mls per gal. in town 15 mls per gl and less it should be way higher

I assume you mean by dumping fuel a drop in gas mileage. What was the sticker fuel estimate and your past experience? How long since the last air filter, fuel filter, plugs etc., and how many miles? What do you mean by computer resets?

Got some bad news, dude. www.fueleconomy.gov says you’re getting about the fuel mileage this car gets. You actually seem to be getting better hwy mileage than EPA tested, but about as good as it gets based on other owners. Maybe a tune-up can help get the city mileage up a bit. Also, try to keep the RPMs from getting above 2400. This will help improve the city mileage too.

Where are you getting your numbers from? You are not getting 27-28 hwy, nor 24 “rural”. 15 in town is the only plausible number you posted. You might be able to squeeze a max of about 24 hwy out of that van - if you drove it explicitly with fuel economy in mind.

So … you might want to say how you’re figuring mpg.

+1 BustedKnuckles and cigroller.
Getting 28 miles on a 3.5 liter engine is phenomenal, unless your commute consists of driving down a really steep hill, both ways, with wind in the back both ways.
If you’re getting 24, you are doing really well.

The car is an 01 chrysler 300m 3.5l, fuel filter was changed, fuel system cleaned, two 02 censors changed, new plugs. The machanics hooked it up to a computer and drove it on a route that includes city, rural and highway. My past milage for the car was about 390 per tank and now around 180 miles per tank under the same driving conditions. 24 mls rural 27 hwy is what it should be at but my milage even on the hwy is 15.104. sorry for the confution! upon every startup the engine revs to 1700+ rpm’s, then back down to normal to idle… with exaust rich with gas

You seem to be talking about a fairly drastic/noticeable change then. The most common reason a change this large would come on would be a malfunctioning thermostat or coolant temperature sensor. If the thermostat sticks open and/or the coolant temp sensor reads too low a temp then the car will run rich constantly - as if you’re driving around all of the time with the choke on.

That would be my best shot at it, anyway - in addition to making sure that all of the other normal stuff is in order like tires, tire pressure, alignment.

Do u think it is normal the rpm rev on start-ups for this car? the machanic wants to put in a new mass air sensor

I’d try cleaning the maf sensor before replacing it.