92 Cutlass rough idle, no service engine light

I have a 92 Cutlass Supreme 3.1 v6. One day all is good, the next morning starts but idle rough, missing, lack power on take off and shutters. After car ger moving when it shifts into overdrive shutter in very noticeable. Changed plugs, wires, fuel filter, cleaned egr, iac. same problem. I have no "service engine light", but light works. Please help.

Welcome to AF, many things can cause this, low fuel pressure, dirty/clogged/inoperative injectors, bad coil. Tough to tell from here, start by checking FP.

What will be the best way to do this? Plug in a pressure gauge at on the fuel rail?

Correct, you need at least 37 psi.

What problem would a blocked/ defective cat. convertor cause? Would it cause the SES light to come on?

Usually not on pre obd11 cars, no power on hard acceleration and a whistling or vacuum type sound from the exhaust.

Found bad coil, replaced runs good