2000 Galant 2.4 SOHC - Bad/Low Idling

Okay...

Driving down the freeway, the timing belt broke (thank God the motor is a non-interference motor)... :-) So replaced the timing belt, balance belt, etc (see more below)...

Current Problem: Car has a bad/low idle (around 500-600 rpm), and make the whole motor shake (due to this bad/low idle)... PS, when gas pedal is pressed, and the rpm's are increased, the motor runs perfect... Great acceleration, great power, etc... Only problem is the bad/low idling... PS, this wasn't any problem prior to the timing belt breaking, and the replacement... It's something new...

Any ideas on what is causing bad/low idling?

Note: Just finished completing a timing & balance belt replacement. This was done correctly, starting with the balance belt, then the timing belt... All pulleys, and tensioners were replaced as well... Also, the right side oil sproket that works in conjunction with the balance shafts was correctly timed (IE, screwdriver fit 2.5 inches into the block hole)... So, pretty sure everything was installed correctly...

Again, any ideas on what is causing bad/low idling?

Thanks for your support in advance... :-)