I m having a weird issue with my 97 maxima at startup, especially when cold. The engine starts fine but the rpms drop precariously low to the point I think its gona shut off, but then jumps right back up to its normal idle. It never has done this before but started showing these symptoms after using a bottle of STP fuel system cleaner additive to my gas tank. Anyone have an idea how to fix this?

 

Clear your Idle Air Control valve and your throttle body. Should go away.

-matt