I have a 1999 F350 7.3L powerstroke 285K miles. I havent had it long (couple months) but want to learn how to DIY as most people do on PSN. It has been hard to start ever since I had it (winter time). Had it plugged in for about an hour and went to crank it and it turned over normal for about 5 seconds and then suddenly slowed down cranking like a battery dropped out or something. I cleaned the terminals and charged batteries. After this the batteries had much better connection and cranked fast but I noticed no wait to start light. I have checked all the fuses and all are good.I put a new GPR on but no change. Any ideas?