Intermitent hard and no start.

'96 XJ
I searched and didn't find much help on this. there was one similar but didn't have many replies.

about half the time, I can get a normal, strong start. After a few strong ones, I start getting weaker, slower starts, like the battery is failing. Eventually it gets down to the point that it won't start. The starter won't click, but will instead slowly crank the engine, not nearly fast enough to start. After about 5 minutes, it will start strong again. No boost or other intervention needed. Then the cycle will start over again.

Internal accessories don't show any sign of lack of power from the battery when in the poor start part of this cycle, and the battery is a couple of weeks old.

Battery connections have been replaced as they were heavilly corroded, but problem persists.

Bad starter...

Nick

... or high resistance in the + cable to the starter
... or poor ground connection between starter and engine
... but most likely bad starter.

The worsening of the symptom over use of that particular piece of hardware points to the starter itself as a very likely suspect.