1999 Chrysler Sebring engine RPM problem

Need to know the engine size when talking about an engine running problem. Also need to know the exact code number to interpret it properly. One is for loss of camshaft position sensor signal. A totally different code is for loss of crankshaft position sensor signal. Some engines will continue to run if the signal is lost from one of the sensors but they usually will not restart if one signal is missing.

A transmission shifting problem should not be related to those two sensors. If it stays in second gear, which is "limp" mode to allow you to drive slowly to a repair shop without needing a tow truck, there will be a diagnostic fault code in the Transmission Computer. Most code readers used by the parts store people don't access anything other than Engine Computer codes so you might need to visit a mechanic with a scanner to have those read.

Holler back when you have the codes checked in the Engine and Transmission Computers. Those may shed some light on what's happening.

Hope you're saying the problem is fixed, but the alternator didn't damage the camshaft position sensor in the distributor or the crankshaft position sensor. Those are powered by the Engine Computer with a very carefully regulated 5.0 volts. If the alternator quits, the engine will still run on the battery for about an hour. If the voltage regulator inside the Engine Computer shorts, which is extremely uncommon, system voltage will go too high, but the computer will still regulate that 5.0 volts. I have never heard of an alternator taking out a sensor. I taught Automotive Electronics for nine years, and we spent a lot of time on charging systems. There is nothing I can think of on a Chrysler product that could do that.

I suspect you had two unrelated problems. Failure of the crankshaft position sensor is somewhat common, and the brushes can wear down in the alternator. Those can be replaced very inexpensively, but most people just replace the entire alternator.