SR oxygen sensor problems

[srJOEYdet]

I have a 91 S13 with a 91 redtop from a 180SX. It has a bolt in the exhaust menifold currently, becuase I just sent my third oxygen sensor back to courtesy nissan. My first one I got from autozone, and my second one was from baxter auto parts. All three are the right size (the small one), but all three had the wrong plug, and did not read correctly. They had 4 pin square plugs, using 3 pins, and the plug on my harness is a 3 pin plug, oval casing.

The sensor from courtesy nissan was from a Z31 300SX turbo. I let the guy look up the part # for me, he said he was familiar with SRs. THe part number on the invoice and the box is: 22690-21P11

When plugged into my car it reads 200mv constantly. It goes down to 190 mv if you rev it hard. This is at a stand still, with the car warmed up (about 800ºF EGT). When the car is in motion, it reads lean all the time, and never changes on my autometer AF gauge. The gauge has 12v, and is hooked up proporly. I probably have at least 10 hours of experience soldering, and All my wiring is proporly soldered.

I am trying to firure this one out, so if anyone has any thoughts, please share.

Joey