Starter motor on your 1988 rx7 is only kicking over at half the pace if not slower than normal?

My 88 had the same problem. Turns out the alternator was not quite charging the battery to full level. The battery should be charged to 12.4 to 12.6V (room temperature, new battery=12.6V). Adding distilled water to the battery did not solve the problem (try this first). The alternator was only charging it to 12.1V.