1995 F150 - Can not fix! Help!

I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but then it will bog under part throttle, pop back and run crappy until wide open
throttle then it takes off and runs great. Always runs great at wide open throttle. Occasionally it will stumble at an idle but most of the time it idles perfect. It gives a lean code but as it is obd 1(stupid as I call it) no data stream. Here is what I have done so far. A lot of this is as it is my sons first truck and I just want it all ready as soon as he gets his license in the next month.
New plugs, wires, cap, rotor & distributor Changed computer - same exact symptoms as the original one Fuel pressure test while driving on two tanks all is fine New mass air New fuel filter New throttle position sensor Cat is punched out O2 sensor was replaced before I got it Cleaned all grounds
It doesn't skip or run bad on any cylinder but just like something is not telling the injectors to open all of the way until you hit wide open throttle then it goes great. It is worse up a hill but will do it on the flat also. The check engine light will cycle on and off but only shows the lean bank 1 code. I am hoping the different computer may come up with a new code.
Thanks in advance for all of your suggestions!
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Why just do a job when you can OVERKILL it!



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LOOK2X wrote:

Clean or replace IAC valve, clean EGR channels, clean or replace EVR filter. This site for GENERAL Engine (5.0 engine) covers most conditions: http://www.lincolnsonline.com/tech/tech.html
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OBD-I isn't that stupid, a lean code is still a lean code. That's your first clue. Do you smell gas when it bogs down? Someone stop me if I am wrong but I think a lean condition (probably a vacuum leak) might tell the computer to richen the mixture with more gas, which could be why your bogging down at part throttle.
See any codes for "adaptive rich limit"?
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