86 6.9 Starts fine, Runs fine, no smoke but no power
 

I read though all of the loss of power treads, didn't see any like my problem. I have a 1986 Ford F250 6.9 IDI, She starts fine, runs fine and no smoke but she is the slowest truck I have ever had. Getting on the freeway is scary, From a dead stop I have to floor it to just get up to regular in town driving speed (35 - 40 mph). I can get it up to 55 to 60 mph on the freeway but Heaven forbid I have to climb a small hill, she;ll drop down to 30 to 35 mph with it floored. I keep thinking that maybe she just tired at 245,000 miles. I need to try to find out what the problem is, ie fuel pressure, dirty injectors. I have worked on gas engines all my life, but I'm new at diesels. Could anyone give me a list of possibilities:argh:? I don't mind learning, but I need a place to start. Thank you
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