Which cells are getting hot? The cells in the middle of a pack should be hotter than those on the edges, sinc they are surrounded by other hot cells instead of cool refreshing air.

If you really want to match cells, you will need a charger /discharger that can monitor each cell individually, like a TurboMatcher or a Futaba CDR-5000, both of which are very expensive. That way you can cycle banks of cells yet still get results for each one.

With the Futaba, you will have to rig some kind of thing (like a plasitc board with four sets of connected terminals) into which you can pop at least four cells, then attach its monitoring harness and cycle away. You will be able to get average votlage and capacity for each cell at up to 40 amp discharge rates (which is way too much...30 should do it).

Be aware however, that discharing cells at 30a damages them. Typically, the numbers you see (run time) on matched cells represent the runtime it had during its first few 30a discharge cycles. You would be lucky to ever get that kind of run time out of them again.

This is why matched cells are a tradeoff...you get the voltage performance, but the run time is a little less. However, this is an academic difference...you won't notice it when you run your car, as the difference can be as little as 30 seconds.