CelicaRacer05, each Celica has a different battery in it depending on what model you own (GT or GTS) and what package you have installed (none, Weather / Full) - And also what year your Celica is.
If you have a 2000 Celica GT - then chances are that you are with the shit battery and you may need to replace it.
Go ahead and spend the $60 to $90 for a new battery - you'll not only love the reliability and new found faith - but you might also notice the added power
NOTES: The best mod i ever did was remove the crap stock battery from my celi and replace it with a sears diehard gold
$70.. and self install was done in less than 15 minutes (in sears' parkinglot