Help, I have been having problems with my RX8 here is what been going on

2004 manual RX8

I put a new battery in since this the car has been having electrical issues such as

when I rev the car sometimes the stereo will shut off for a second and the dash resets?
my power steering has stopped working,
also my check in light comes on if I get on the car and then it will only go like 30 mph?

I have never experienced this when the old battery was in the car but it wasn't keeping a charge so I replaced it and now I get all this? I am not working at this time so I cant afford to take it to the Dealer. this car is my fourth RX

Thanks Sky

 

Are your connections clean & tight and have you checked the charging system (belt adjustment and charging voltage/amperage)?

 

Do you have access to a multi-meter to check actual outputs of the alternator and battery when under load? If you do, might be worthwhile tests to perform. Attached is an alternator test process you could try - it is a generic procedure (not RX8 specific) but it is valid. If you find you need a new alternator, one place to try for an OEM replacement is Alternator Pros. I've been happy with the replacement unit I got from them.