I have a 98 Ford Ranger, 5 speed MT. When first started, the engine runs fine, but after the engine heats up a bit, it will peg out. This is really noticeable when at a stop light with the clutch depressed. It will run at max RPM's for a while and then suddenly drop off to nornmal. Once the light turns green though, the trouble returns. The only recourse I have is to put it in 5th gear and almost bog the engine down. I've replaced every vacuum related part, springs and even adjusted the idle to as low as I could get and still maintain the engine running.. I have been told that the Fan clutch is failing and should replace it, but this couldn't be the problem, could it? I have acquired some .45 caliber Jacketed Hollow-points and am thinking of taking her out to pasture. She's been good to me, so I'd like to keep her around a bit longer..