the car went from very high idle to very low idle can someone help me.

the car is a 95 camaro 3.4L

when the car was at high idle i replaced the tps and idle air control valve and it remained the same a few days later i started the car and i was and about 500 rpms so yeah its been givein me some problems lately can someone help me

 

well i drove the car the other day and it runs fine; its only at idle where it starts to misbehave any ideas

 

my 2000 ss camaro did the same it would run at 1200 rpms then run down to 400 some times mine was my battery was very weak

 

check the grounds on the block to from and fram to batt