P0336 Code and rough Idle 2000 V70

[Volvo Manic]

I have a rough idling Volvo 2000 V70. It is surging between approximately 700 to 1000 rpm, continuously at idle. I just cleaned the throttle body but did not take the ETM apart to inspect/repair/clean it. I thought I was tracking down an ETM problem but now I am not so sure. Previously it was hesitating in acceleration from a stop. Major hesitation with two or three kicks and misses before it took off.
It has 150,000 miles on it, and its a USA model, non-turbo. Has the white tag on the ETM (yuck) I'm trying to resuscitate it from a previous hard life. I installed a new camshaft position valve about a year ago when I got it as that was shot.
I see that is the code for P0336 - Crankshaft Position Sensor Circuit A Range/Performance. Has anyone had experience with replacing that sensor before? Also I'm wondering if that is the crankshaft sensor I see on the top of the motor coming out just above the ETM on what looks like an output from the camshaft. If not then I need to locate it and try and reroute the wire coming off of the sensor, but I just do not see another crankshaft sensor now.

Thanks Volvo enthusiasts.