well i would have the timing belt checled out first, i have heard for good mechanics that our engines are very, very touchy, if he missed ny 1 tooth it could be major problems....also if you had the throttle body worked on i would check the sensors in the tps....sounds like a idle control problem....have you checked the code?....put the key in the ign. and turn to the "on" position and back to the "off" position 3 times (on-off-on-off-on) and look at the check engine light(note you do not start the car and on the third turn to the "on" position look at the CEL (check engine light) and count the number of times it flashes... it will flash in a sequence like on,on,on,on....on....this would be a 41 code for ex.
the last code given will be a on,on,on,on,on.....on,on,on,on,on....which is 55 end of codes
if infact this is a 420a engine you can get the general codes list online i will post a link in a minute...but there are some things that you really need a scan tool to diagnose.

thanks rob
louisville, ky
97 rs
enki17x7
magnacore
groundcontrol
hahnstage1
greddycatback
struttowerbar
nittosrear
khumosfront
shortshift
lightnedflywheel
knfiltercharge coldair/intake
blitzturbotimer
autometer a/f ratio
autometer boost guage
CENTERFORCE DUAL FRICTION

Lyndon@bluegrass.net