location sensor oldmobile

i have an 2001 olds aurora with 148k miles on it 4.0 liter just bought car 3 wks go. when the car warms up sometimes it stalls when driving down the road sometime it surges forward with the tech-m and the gas hand going haywire
i have read on the board about it having problems with upper and lower crankshaft sensors i'm considering replacing both is there an how to to do this and where is the location of the sensors on a 4.0 liter engine. found on 3.5L any pic or videos would greatly be appreciated.any ideas or suggestions. thanks in advance.

come on anybody

Instead of waiting for reply that may not come just do a search of the forum. Here are a few to get you going.

Crank Position Sensor #1 (http://www.automotiveforums.com/vbulletin/showthread.php?t=675372&highlight=crank+sensor)

Crank Position Sensor #2 (http://www.automotiveforums.com/vbulletin/showthread.php?t=758458&highlight=crank+sensor)