My 1998 12V has been intermittently cranking slow for about 6 months. Recently it started happening more often and more severely. It would crank slow and then sometimes stop turning at all but with the starter still trying. I assumed it was the batteries so the first time I couldn't get it to start at all (about a week ago) I bought 2 brand new Exides. No change. I can still get it to start after a few tries and once it starts it runs great. No smoke, no noise, good power. I checked the resistance of the battery cables and they were fine so I pulled the starter. It had never been out before and with 220k and a lot of short trips I figured it was toast and took it to be rebuilt by a very good local shop. They reported that the contacts were rough and the armature was shorted and did a full rebuild. I put it back in tonight and... no change. By watching the fan when cranking it seems to go normal speed until it gets to a certain point and then the engine just stops and the starter strains against it. Again once it does start it runs great. With a socket on the alternator I can turn the engine but it is pretty stiff in some spots. I checked the coolant and oil and they aren't mixed so I don't think a leaking head gasket is allowing water into a cylinder and hydro-locking it. I also took the belt off in case the AC compressor, alternator, or something is causing an issue. No change without the belt. That's as far as my diagnostic brain can go tonight. Any ideas here? Could the PS pump, vacuum pump. or injection pump cause this?