My vehicle loses power when I try to accelerate, ive cleanded the tank new fuel pump new evr new fuel filter. I own a 98 e 150 van

Check vacuum lines.

It might not be getting enough fuel due to a dirty fuel filter, air filter or a failing fuel pump. I'd try a new fuel filter & air filter first then check out the pressure on the fuel pump. You may also have injector problems.
Good luck.

Do you have a fuel pump? If its bad or weak, you aren't getting enough gas to your engine. Has anyone thought of the filter in your gas tank?

i'm not sure what the psi from the pump should be, but it could be that it can't keep up with the quick acceleration since you said it was slow to build pressure. I would start with the cheapest first and change the plugs and air filter see if it improves, before I spent the money on a pump. if it turns out they are the problem it never hurts to have fresh plugs and air filter at least then you know what you have in it

For acceleration problem,the help links are provided below,click the link below to go through its procedure :----Engine accelerates when brake is applied? http://technoanswers.blogspot.in/2012/02/engine-accelerates-when-brake-is.html ----------
Loss of acceleration? http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html
----------How exactly the Vehicles Accelerator Cable works?

http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-cable.html

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How exactly Vehicles Accelerator Pump Diaphragm Works?

http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-pump.html

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accelerator pedal sensor? http://technoanswers.blogspot.in/2012/02/2009-chevy-impala-accelerator-pedal.html

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stalls and bucks on Acceleration? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

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Acceleration lag problem? http://repairhelpcenter.blogspot.com/2012/01/acceleration-lag-problem.html

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Car loses power while acceleration? http://schematicsdiagram.blogspot.com/2011/12/car-loses-power-while-acceleration.html

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This will help.

Thanks.

you may need to get your injectors cleaned the fuel filter being changed is good the coil is another good one or your fuel pump could be weak and isnt giving the proper psi of fuel to the injectors so id say clean the injectors first if thats not it the fuel pump

sounds like fuel pump is going. should be 40 psi after fuel filter on driver side firewall.

go here for help

http://groups.yahoo.com/group/villagerquest/

cartrigde type is locted at the top of the crossmember just forward of the gas tank on driver side of the vehicle,,,,,,,,non cartradge type located on front of the fuel tank..

make sure the air filter is intact and clean, the engine needs to breathe
do you have fuel pressure?
how about spark, do you have a good spark ?
change plugs and wires

Sounds like there is a load of dirty fuel in that gas tank. Ran good for a while after changing fuel filter, then began to run poorly again. Remove fuel tank, drain and clean out, replace fuel filter AGAIN. That should cure it. Hope this helps