couple issues. p0483 fan code, excessive rp code

truck feels under powered. My rp gauge shows 24k rolling at cruise speed

and wot itll peg the gauge out. i hear lots of people draining the rail, but i

feel that im gonna blow something up. I dont have any hard starts or white

smoke to indicate injectors. my fp is 18psi so i think my cp3 is still in ok

shape(measured @ fuel filter).

I get the soft code p0483 daily, im not sure whats causing that, truck

doesnt overheat at all. could this code be causing the underpower issue?

truck used to run real hard, now its just ok.. really feel like somethings going on.

thanks
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05 3/4 4dr swb 4x4 6sp, smarty beta, custom intake,fresh valve adjustment. 90 nozzles and arson III kit, rator 150, 64/65/12