My 2003 Liberty 200k+ miles with 3.7 V6 is slow cranking over. For the last week or so it seems to be getting slower but is inconsistent. Yesterday morning, it cranked pretty slow in my 70-degree garage. After work it cranked better but slow, and the temp was 55-degrees outside. I drove for 10 minutes and stopped for gas, and it cranked really slow but started. I drove 20 minutes home; shut off the Jeep; and tried to re-start; and it cranked just a little and would not start. About 5 minutes later, it cranked slowly and started. This morning it cranked a little slow but not bad. Battery is 2-1/2 years old and shows 12.4 volts when Jeep is not running. Shows 13.8 volts when running at idle, so I think the alternator is OK. Load checked the battery with cheap harbor freight load tester, and it checked OK. There are no other problem and no warning lights. I put a trickle charger (2 amps) on the battery overnight, and it made no difference. Any advice? I am thinking about installing a new battery because it is easy, and I have had bad batteries do some strange and inconsistent problems (but hate just changing out parts). I think it could be the starter; but I have never experienced a starter slowly dying; and it is difficult to replace. I have done a lot of searching on this forum, but I am not confident in my trouble shooting so far. Thank you.