A blue oval buddy of mine has a 2000 F-150 w/ a Harley Davidson series blower on it. It ran strong for about 9000 miles but now the power and boost goes away after 1/2-3/4 throttle. We changed the MAF and fuel pumps to no avail.. The transmission has been having a tough time lately it has about 110,000 miles on it. IMO the power loss is from the converter or transmission.
Any suggestions?

sound dumb but have you change the fuel filter, a friend of mine had a f150 w/a 5.4 that have the same problem we almost put a trans in it but it turned out it was the fuel filter.