I just bought a used DVX90 for my son and there are some issues.

1. It stalls periodically, and it seems to be due to to low an idle level, but if I adjust the idle up it will be fine for a while and then the idle seems to become too high, then I lower it and all is fine for a while then it will drop so it is to low and stall. I wanted to make sure the idle mixture screw was within spec but it is not a screw I have ever seen, it has a flat face, all round with a small flat spot on one side??? It starts very easily, idles perfect until he starts driving and then the idle acts up.

2. The other day he went through some puddles and then the starter would not work, nothing would happen when starter wa pushed but it could be started with kickstart and would run fine, I guess this could be in the brake safety switch, starter relay, starter switch...are there any common causes?

3. Shifting gears, when shifted into reverse it must be reved up a bit to engage, seems like this will cause damage, is this normal dealer tried to tell me it is.

Thanks for any help