It was ignition related. I hooked the timing lead to each plug wire and found that #4 was firing but very erratic. On an unrelated note, a plastic timing light does not fare well if it slips out of your hand and lands in the mechanical fan. $99 case of butter fingers there.
I pulled the #4 plug and it was pretty wet, but it the edges were sharp. I replaced it for good measure. I did notice that it was not near as tight as I would have expected. There was also a little residue around the plug on the head. I wonder if it wasn't getting a little blow by for some time.
After replacing the plug, I started it and still noticed a weak and erratic spark on #4. Popped the cap and everything under the cap looked good. I inspected the rotor and found that the screw locking down the adjustable rotor was loose. Added a bit of Loctite and tightened it back up. I could see an depression in the plastic from the washer and lined it back up there. Checked it at 2000 rpms and it was still spot on for timing.
I think I had two things going on. A somewhat loose plug and the loose rotor. Took it for a test drive and the readings on the FITECH were far more consistent and smooth. AFR values were much smoother, especially on the analog gauge on the dash (02 sensor is on the even side of the motor). Trim values were much smoother. It drove better than it ever had. MAP readings at 70 mph went from 45-48 to 37-38. Motor is working way more efficiently. Gonna have to drive it a while to let it fine tune the tables.
Thanks for all of the help from everyone.
Quick question about spark plugs. Mine are Autolite 25. It's been a while since I've looked at plugs, but I remember my previous Pontiac motors having a metal crush washer on them. The Autolite's seem like they use a taper to seal the hole. Do I have the right plugs? Little miffed that one was loose. I installed them 5000 miles ago while the engine was out and on the stand. I could see not getting one torqued well with the motor in the car and fighting all the obstacles but not on the engine stand. Live and learn.
Makes me want to check the torque on all of them when its back on the lift. I have to get the passenger side ones from below. Between AC and the G Braces, its almost impossible to get to them from the top.
Thanks again.
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