1995 Passport 3.2L BackFires?

[1stPassport]

3.2l SOHC 4x4. EX/LX
Has 171,500K and runs REALLY well all things considered.
No Oil Burn, no "Marking its Territory"
4 wheel drive is satisfyingly quiet and smooth with no complaints fron the joints.
I am getting a BackFire Under 2,000RPM? <---Im adding injector cleaner every tank, w/premium too...
Ive done the plugs/wires, fuel filter, radiator flush, new battery cabels, air filter, new tires, and Im about to
replace the Timing-Belt [kit], and Water Pump... I did read another post about mis-firing,
and "checking-the-coil-packs"; havent found a tester yet.
She runs fairly smooth after a warmup, but consistantly "Sputters/Misfires" under that 2,000RPM???
The misfire occasionally is accompanied by a backfire in 1cylinder~maybe 2cyls and then I get power again.
I dont think its the fuel pump/sending unit but ANY Suggestions are appreciated.
Exhaust system is fine, here in Montana it's really dry all year and we dont really rust anything at all compared to say Mississippi.
Thanks again!

[FL 3.2L]

Exhaust leak? Have you done anything to it since you got it?

[1stPassport]

Yes I edited my 1st post to reflect work done...
I have to say, I bought this from my wifes brother and when I took it for a test drive, the dealership keytag had "Blown Headgasket" written on the back of the tag. It also has a Towing Package installed, but it appears to have been very well cared for. I replaced the fuel filter, and the date on the old one was Oct, 17, 2006. The Undercarriage is immaculate with no scrapes on the skidplate. I think it was garaged most of the time too as the interior is very clean save the missing sunshade for the sun-roof

[FL 3.2L]

Did the plugs look OK? Have you scanned it for codes?

[1stPassport]

Plugs and wires were done by their in house wrench so I didnt see them coming out.
I am expirencing the problem with "sputtering" when I try and take off, and thru that 2,000rpm,
but I really notice it when I mash the pedal vs. when I roll the power on more slowly if that helps any...
No scanning done yet and no CEL. Are codes present without an CEL event?

[FL 3.2L]

Yes, you can have a code without a cel. I'd expect you to see the cel if you were missing badly.

[trooperbc]

Originally Posted by FL 3.2L

Yes, you can have a code without a cel. I'd expect you to see the cel if you were missing badly.

yes, except with pre-1996 OBDI diagnostic systems it seems you can be missing in 5 cylinders and not throw such a code (unlike the OBDII which show even the slightest miss).

i would look for a miss which is showing under load, not uncommon. start with the wires and then the ignition coils and possibly ignition module.

you can start by inspecting in the dark to see if you see sparks ajumping, especially when you rev it. but it may be difficult to duplicate without the load. the cheapy ignition pen testers from the bigboxpartsstores can be helpful in diagnosing and spotting the miss. as can the old remove a plug connector at a time and note the rpm drop -- no drop means that's the problem (be sure to disconnect the throttle positioner first or it will compensate and you won't get the rpm drop).
you can also use an inductive timing light to sometimes spot a miss.
if you find two cylinders exhibiting the same miss, see if they are both fired by the same ignition coil. you can easily swap the coils to verify.

//bc

[1stPassport]

Thanks for the starting point. I have classes this week, and a couple of double shifts I need to pull this weekend....

PS, the RightHand side Instrument Lights are burnt out, does anyone have a diagram from alldata for the screw locations on the cluster? Far as I can tell there are only 2 on the bottom; However, I would hate to assume that was all and be wrong/damage the housing...

Can anyone tell me what the torque requirements are for re-installing the pulley[s]? and covers? maybe im missing it in another post...