My truck has been doing this for probably about a month now. When you go to crank it after setting all night it will act like the battery is almost out of juice and turn the crank really slow. But even though it turns the crank slowly, it fires up after the second rotation. Then, if you drive it somewhere and shut off and come back about an hour later, it will crank like normal. I had the battery checked, the alternator, and I replaced the starter because the old one was bad. I didn't have this problem when I put the new starter on in the spring, but I noticed that there is a oil leak coming from around one of the cylinder head bolts, and the starter has a heavy film of oil on it. Do you think this is causing it to short or ground on something? Also, I noticed that my radio speakers always crackle a little even if the truck hasn't been running for day or two. Maybe my speakers are drawing current? What do y'all think?
It's a 1997 4.2 V6 f150.