Elantra starts to die when idling
 

2002 Hyundai Elantra. 133,000 miles. Problem started awhile back when the car sits for awhile (over 4 hours or so) and then I start it and try to drive off, the car would start to go and then completely bog out. I would have to shift into nutral, rev the engine and then go. Service was no help, we replaced timing belt along with all other beltsbut itnever fixed the problem. That was a year or so ago. Now I have bigger problems. When idling, the car starts to sputter and almost die. I have to switch off my a/c or give the car gas while idling. Sometimes it idles fine, but it's getting worse & worse. The check engine light came on and I took it in. Cylinder 1 was misfiring. We replaced the plugs and wires (this was overdue anyways ). didn't fix the problem. Then we replaced the coils...still didn't fix the problem. I'm idling at 500rpms...when the car starts to act up...the rpms drop to about 300-400. I asked if they could adjust the rmps but since the computer controls that, they adjusted the cable. Unfortuantely when I left I was idling around 1400 rpms and had to immediately turn around & go back so they could re-adjust. Now I'm idling at 600 rmps (when running normal) but I still have the same problem. My husband thinks they may have ajdusted the cruiseby accident. when I am stopping at a light, sometimes the engine revs for no reason even when I'm stopped and then after a second it drops down (this only started after they adjusted the cable). My brother says the idling problemcould be the ignition module, someone else said a fuel sensor? I can't keep dumping money into this car and it not be fixed! PLS HELP.

Thx.
S.A.S.