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1985 f250 Explorer edition, 6.9 idi, 2wd, c6, 10.25 rear end
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Discussion Starter · #1 ·
I have a 1985 f250, with a 6.9 idi and a c6 transmission and Im experiencing top end speed loss.
When I bought the truck, it would run about 65 mph @ 3500 rpm. Injectors were leaking, so I replaced all 8 and replaced all the filters on the truck. Also replaced the alternator. Right after replacing the injectors, I lost 10 mph on my top speed. Was running 55 @ 3500 rpm. It was doing this for a while until I regeared my differential to 3.73's. When I took it on that road test it had gained its power back and I was going 70 mph @ 3000 rpm. The truck was running weird and would get random power surges when I was driving it. Like it would be climbing slowly and then just run like a bat out of hell for a second and go back to normal. It went back to being slow the next day and now I'm topping out at 63 [email protected] 3500 rpm.
Sorry for the lengthy post, I dont know much about these engines and could not find any forums with my problem. What could be causing this issue?
 
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