Idle not correct when slowing or stopping

I'm having issues with idling. When driving at low speeds or coming to a stop, the car doesn't want to idle correctly. The RPMs fluctuate and the engine sounds like it's going to die (It usually doesn't, but has on occasion). As long as my foot is on the accelerator, I don't have any problems, however, it does hesitate when I press on it initially. I mostly have problems when the car is warm, and I'm having to make lots of starts and stops. Sometimes when driving down the interstate I let off the accelerator pedal and notice the RPMs pulsating slightly, but as I put my foot back on the pedal, it hesitates and then goes normally. Also sometimes when driving the 'Service Engine Soon' light comes on for a short while but always goes off on its own (This has happened 3 or 4 times now). The other day, a friend noticed that the EGR valve was loose at the bottom of the tube, so I took it off and replaced the gasket, but I'm still having the same problems. I don't have much money to spend, and I can't get the codes scanned at AutoZone because it's an OBD1.