Hello Bob:

I will try to answer your questions one at a time as best I can. I will cite my sources. Remember you and other Brickboarders are more knowledgeable about cars and Volvos than I am. Nonetheless, you and I share a like experiece having recently bought the same used car and now doing preventive maintenance and repairs.

I too have experienced that slight miss and initial stumble on acceleration. I changed engine oil, ATF, PS fluid and differential oil all to Mobil 1 synthetics, changed al filters, etc. Coil packs looked absolutely brand new on my car. The local Volvo dealer charged for changing sparkplugs a month or two before I bought the car. Nonetheless, the sparkplug electrodes were dirty with heavy deposits when I checked them. Sparkplugs also had a rust like discoloration where the ceramic insulation meets the metal head. As you know, I found cooked crumbling insulation on the female connectors at the coil packs. Since you find heat discoloration at insulators, you may want to check (female) barrels for oxydation, heat discoloration, etc. You can also check for voltage drop between ignition wires, coil female connectors and male connectors on the coil packs. What information I have from ALLDATA says ignition coil primary resistance at terminals #1 and #15 is 0.5 Ohms. I do not know what voltage is suposed to be.

ALLDATA says:

TROUBLE CODE CONDITIONS

If idle air trim is allowed to raise or lower air mass flow through the valve too much to maintain even idle, Diagnostic Trouble Code (DTC) 2-3-3 is set.

SUBSTITUTE VALUES

None

FAULT SOURCES

Blocked air filter or air intake

Contact resistance in connectors

Air leakage

Incorrectly adjusted throttle

Defective Idle Air Control (IAC) valve

FAULT SYMPTOMS

Idle too high or too low

My Volvo 960 (1995) has two OBD I modules labeled A and B. Socket #6 is empty (no female connector) in module A. There is a female connector in socket #6 in module B. Maybe this helps.

ALLDATA says ignition timing is 10 degrees BTDC at 750 RPM and the crankshaft position/speed sensor resistance is 200-400 Ohms. I do not know whether this helps you.

I think that is all I can tell you. Hopefully, you will get more help from a more knowledgeable source. You may want to read experiences Joe and Roy posted at BB S90-V90 forum on July 16. I have had their problems with suspension and other things too. Best regards.