Hi I have a 2001 F250 SD 2WD pickup with 171K miles on it. It gets used a bit for around town driving, and a few travel trailer trips each year. It's always been hard starting in cold weather, and I've gotten around this by using the block heater. With an overnight heating cycle, it starts right up. If I'm somewhere where it can't be plugged in overnight, it takes many tries to get it to fire. I've been through a series of new batteries, and I've taken to just replacing them every two years. The usual cold start process without the block heater is to the turn the key on, and wait about 20 seconds until I hear a relay click (off?) which I believe is the glow plug relay, then try to start. This can take anywhere from 5 to 30 tries of this cycle to get it to finally fire. On the cold days, the batteries will give up first. Now, there is a new issue which is adding to the problem. Even in summer weather, the first couple of engine cranking cycles act as though the batteries are weak or almost dead, but as I try more times, the cranking gets better, eventually the truck will start. I replaced both batteries with new ones yesterday, verified the terminals are all clean and tight, and today it made no difference. The first few cranking tries act as though the batteries are almost dead. Could this be a starter problem, with it drawing a LOT of current when cold, then getting a bit better after some cranking? I was going to attack the cold start problem one thing at a time, batteries were first on my list but that's obviously not the issue. I was thinking the glow plug relay next, as easy to change and not expensive. The next step would be to have a shop dive into the glow plug situation.