guys i need some help here
I have a 1994 Nissan Altima GXE with roughly 146000 miles on it
the engine is idling roughly...I had the spark plugs, wires, rotor, and distrubator changed. It still idles rough this only happens up to 45 mphs
THe plugs and wire were changed by a local mechanic. He said it could be the #3 cylinder. But they werent sure..THey also said the injectors seem to be working right. I have read numerous thigns online about the cam sensor and other small things like this that could cause this

Anyone have any suggestions
Thanks
Eli

o2 sensor maybe?