CHECK ENGINE LIGHT??? HELP!!?

I have a 91 camaro RS 350 TBI the check engine light came on recently and i had to use a key to check to see what code it was .. it was blinking a code 21 which is a throttle position sensor so i replaced the TPS with a new one and the drove a couple miles and the engine light went away but then a day later it came on again but it will only come on for a couple of seconds to a minute and then shut off again and when i checked the code again it again said it was a code 21 and 22 which are both TPS so i dont kno what else could be wrong withe the tps since it has already been replaced what is it this time?