Have a 1999 F-350 powerstroke that is hard to start. Put New batteries on and It sounds like they are week on the first crank. Turn the key off and cycle the glowplugs again and it will turn over normally. May not start then either have to cycle the gp several times. Wondering if the GPR might be bad or the Glowplugs also. Got over 300000 miles on it neither have been changed. Sure it wouldn't hurt anything to change them. Any advice would be appreciated.