Trying to help a friend ...The Brick is a '91 245.

I did a quick once around so it might pass emissions now BUT if it doesn't, where do we look next?

I don't have the previous emissions numbers but here's what we did to the car.

Fuel pump regulator; Seemed bad,wet hose; we replaced it

Throttle body; Dirty, took off and cleaned. Switch was set correctly.

AMM buzzed out at 3.5 ohms between pins 2 and 3. Bentley says that's a good AMM

Big Bellows: no holes and not to gacked up at all, so that's OK

O2 sensor replaced. Can someone run through the test for that? The more I read the more confused I got. It's a 3 wire type. What gets disconnected and what stays connected. What do I check to GROUND?

New plugs, new wires and new Rotor/Cap.

Idle Control Valve was taken out, jumped with 12V and it snapped back and forth nicely. So that seems OK

Flame trap was cleaned. Ohhhh, I didn't check the nipple. The small hose was clear, don't know about the nipple to the intake though.

The ECU; they don't usually die this way from what I read. They usually just die. Is that correct?
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me