My 01 7.3 Powerstroke has 174,000 miles. It's not hard to start even if it hasn't been plugged in, but once it's started it takes forever to warm up. If you try to drive it before 5 min or so it has no power and will even die and throw white smoke out of the exhaust. When it does die it's very hard to get to start again. I'm planning on replacing the glow plug tomorrow but I'm a little worried becuase it's only hard to start after it's been running for a short time. I did replace the fuel and air filter withing the last few days.

 

Have read in some other forums it may be in injector issue. Just talked to a 20yr Ford mechanic he says no way if it's running fine at operating, try camshaft position sensor. Sounds like a long shot but for 20 bucks why not.

 

If you are going to replace a glow plug , how did you decide which one since there are 8 of them ? There is a program in the PCM that keeps the glow plugs glowing after start up , but at a reduced voltage. It sounds like it isn't working. It would be a wise move to check out the glow plug relay and glow plug module.