Well, a 1 1/2 year old battery is not immediately suspect. But, get it fully charged and have a proper "load test" done on the battery. Make sure that it puts out the rated amperage. Or, borrow a new battery and try it. If the starter spins noticeably faster, then it's the battery. If not, then the starter is suspect.

But, check all the cables to the starter and the cable from the engine block to the body. These get corroded with time and if resistance builds up, the symptoms of a bad battery or a bad starter present themselves when a 10 minute fix with a wire brush is all that you need.

A valve adjustment is required every 15K miles with these engines. Many folks go 25K but that's pushing it. A good mechanic can easily do the job in 2 hours..........some can do it much faster if they are familiar with the 617.