About a week ago I went to start my car and when I turned the key I got a click and nothing else. I waited a second and tried it again and it fired right up. It did it a couple more times that day until I finally got stuck. It would only turn the motor in short pulses and not enough to start it. I got towed home and got a new starter from Ford. I put it in and it cranks good and strong compared to the first, but it still makes a slight rattling noise (not really like a gear grind) when it cranks. On the first startup today it locked up the first few times I tried it, then it fired right up. I'm guessing since it's a new starter that the problem is not the starter itself. When it locks, it "feels" like if the engine were seized or something like it's trying to turn, but just doesn't have enough power. Could the relay cause a problem like this?