94 Sierra turns over slowly with good battery

My starter is turning over very slowly. I replaced the battery, charged the battery (a few times), but it didn't really help. I'm convinced my problem is either the starter or my battery cables going bad. Are these trucks known for problems with either? My truck has 100,000 miles on it. How long do starters normally last? Is there some way to check the starter or the cables to see if they are the problem?

In a word: No, and Yes. I actually work for an aftermarket alternator and starter manufacturer, and have the honor of also manning the tech lines. I'll tell you what I tell a couple dozen people a day. Check for voltage drop at the starter, it should be real close to battery voltage, if not then you have a cable/connection problem. If you think your unit is bad, drop it and take it up to be tested. You can arc the posts on the solonoid to see if it works indepenently of the ignition switch, but it's hard to tell how much resistance it's actually giving to the battery. Good luck.