idle problem
 

hello,
i have a 1987 toyota supra single turbo.

my car seems to b idle'ing a little low at first then when it warms up it seems to b idleing around 1500rpms

also my mechanic thinks it has been "chipped" is this the cause of the idle'ing being too high...?

i dont know much bout electronics so i dont even really know what the term "chipped" means