I CAN'T TELL EXPRESS HOW MUCH THE TEMP2 SENSOR EFFECTS HOW
: > YOUR VAN RUNS...
: > DO THAT FIRST.
: > IF IT'S BAD YOU'LL SEE AN IMMEDIATE FUEL CHANGE.
: > IT MAY ALSO ELIMINATE THE BACKFIRE...

    My reason for saying it might solve your backfire problem is a new
temp2 sensor will be properly regulating fluctuating coolant fluid
temps and the ECU will know if you van is cold or hot.
    It tells the ECU to give your injectors more gas when it's cold
and less when warm.  If it's not working properly and it tells the ECU
to give more gas to a motor that is warm your van will run xx rich and
gas mileage will be down...
    My mileage actually doubled.  Yes doubled.
    I was getting about 10 mpg and it went to 20 mpg with that single
part change.

    Keep you fingers crossed that this helps you. ;0)

                                                                 Debi