Ok so I have had this problem of the car surging at low rpms on the highway for some time noow. I finally decide that its gotta be the coils since the wires all checked out and will had the same symptoms as mine. so im on the way to my dads shop to get it fixed and my car starts jumping. its doing the surge thing but very violently. now the SES light comes on.
I make it to the shop and the code reader says its 341(crank position senor) and 406(egr pintle valve) so we order a crank sensor and a new egr ($180). So we replace the egr valve and the codes go off and the car is fine, runs alot smoother.
So I am still nervous about not replacing the coils or the crank sensor but i take it back to my school. I almost get to the school and the SES light goes on again! So now i have to go back to the shop tomorrow.
Do you guys think these codes have something to do with the coils at all. Are the coils not proving the right voltage to the spark plugs to burn the gas and now the egr valve gets messed cuz of it and then the crank sensor doesnt sense the right mixture so now that kicks off too? Maybe thats what it is. let me know what you think, thanks

bad or intermittent coils won't cause surging....they'll usually not even be noticeable at idle. They usually appear to be a miss under load at high rpm'*, kinda the feeling you get with water in the fuel. Bad plug, wire, or coil will do that.

will, i do notice a bit of a miss under high accel on a slight hill. nothing huge but i noticed it today when i test driving after the egr.

So you dont think that the coils are causing the spark plugs to not spark enough and burn enough fuel? Do those coils even throw codes? I just want this nighmare over with. thanks will

OBD1 won't detect an ignition fault past the ICM. The best thing to troubleshoot this is to pull plugs and inspect them. They can tell the story very well.

thanks will

If you're ignition is fine, they'll all be a spotty tan texture/color. A darker gray and fuel smell is a sign of an ignition problem, leaving unburnt fuel residue on the plug. Since you have to pull them, and they're cheap, I generally replace them when I do this. Just remember which cylinder you found which plug in, if you find a problem.

My bad coil was getting worse at higher temps. It would be better at cold idle, getting progressively worse as the car warmed up. My bad alt contributed to the condition, by means of a weak spark. A new alt, battery, and 3 new coils solved my prob, but I'm glad I didn't just shotgun it. That can get expensive.