98 Windstar - Won't accelerate

I was driving the other night and my 98 Windstar 3.8 started loosing power. If I let off the gas it was ok but if I gave it to much gas it would buck and backfire. I pulled over and nothing looked wrong. I restarted but it would not rev over about 3000rpm. I went the next day and had the filter changed and it improved but still the same problem. I can baby it at around 2000rpm and it ran on the highway to get home and would hold 60mph/100kph.

Is there another filter or screen because it seems that it is starved for fuel.

Not sure if it is related but if reved in neutral it would break down at 4000rpm but I figured that was the computer limiting the rpm's when there is no load

I was thinking of replacing the van since it has 279,000 rusty kms but would like to get another couple of months out of it while I find another Windstar or similar vehicle

Which filter did you replace?

There are 4 different filters on the van air, fuel, oil and cabin.

The first two can cause your problem.

In addition to that a dirty MAF sensor can report an incorrent amount of air entering the system and will cause the problem too. You can give it a good clean with MAF cleaner or electric contact cleaner in case you can't get the first. You can try disconnecting the MAF sensor with the engine off, start it and run the van for a while, don't do it for extended periods because the transmission will shift roughly.

A defective TPS might cause it too, you can try doing the same as with disconnecting the MAF.

Big vacuum leaks can cause that problem too, is the air tube after the air filter properly seated?.

A bad fuel pump not delivering the proper amount/pressure of fuel will cause the engine to fuel starve and it won't accelerate too.

Ignition problems could cause it to some point, but you would also experience misfiring and shaking under load.

Oscar.