I drive a 1990 ford ranger xlt with the 2.9L in it. I have been constantly been getting a code 64, which is to my knowledge is the AIT or Air charge temperature. This apparently has something to do with my maf. The check engine light has been surging on and off for the last week as well. It idles at around 500 rpm when it normally would idle at around 1000. and I am getting terrible gas milage. like I filled my tank yesterday and im down to a 1/4 and I have driven 70 miles. (I also drive conservatively) So I am at a loss.

do you have a California emissions ranger? If you don't, then you don't have a mass air flow sensor. You must have read some information that doesn't pertain to your truck as it wasn't until later on that they even integrated the IAT sensor into the MAF housing.

The MAF sensor if equipped is attached to the air box, it would be inline of the intake tube.

The IAT sensor is located on the driver's side upper intake plenum in the middle runner IIRC.

IMHO I would be checking fuel pressure and for gas in the vacuum line to the fuel pressure regulator to make sure a fuel problem is not a factor.

Clean your IAC it is the round tube on the passenger side of your intake

Disconnect the elec connector to your MAP sensor - it is on the firewall passenger side just behind the intake - it also has a vacuum line that connects to the front of the intake on the pass side - it is a little smaller than a cigarette pack

If it runs better with the MAP sensor disconnected then replace it - very common failure

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1988 Ranger STX, custom built flatbed, winch, 33x 10.5 BFG mudders
1974 Suburban (AKA "the sub") lockers front & rear, 383 cu in not even close to stock motor, snowplow 37 x 12.5 HUMMV tires, 4.56 gears
1952 M38 (CJ3) Jeep - my newest project - 289 ford, hardtop, got it with not one wire in it. Hope to have it driving this year

Thanks guys. Will do that when I get paid on Thursday. In the mean time the trucks been running okay again. I'm gonna take it apart and clean her up a bit. New gaskets and filters all around. Problem stopped on its own for now. Still gonna replace the map sensor and air charge temperature sensor. Will keep your updated. Thanks again.