95 4.3 cylinder 2 misfire

It has been one problem after another. Here are all of the parts replaced (not all of them for this problem) within the last 100 miles.:banghead:

all o2 sensors
exhaust including cat from crossover back
cap, rotor, plugs, wires, all Delco
new CPI Spider and nut kit, upper intake gaskets
Idle Air sensor
TPS sensor
fuel pump and filter

Before the cylinder 2 misfire code showed up it was throwing only a code for the pre cat o2 sensor heater circuit malfunction. Figured it was time for all the o2's so replaced them both and the entire exhaust for good measure. It needed it. Cleared the o2 code and it ran better but not good. No codes. Drove it for about a mile and it threw the cylinder 2 misfire. Replaced the cap and rotor and it went away for another mile and now it's back. You can feel the misfire during acceleration mostly. You can barely tell it's there at idle and cruising. All plugs are new and look fine. Great spark. No arcing on wires. No vacuum leaks that I can tell with carb cleaner. Removed butterfly valve in upper intake and no signs of washing in the intake. Fuel pressure is great. No loss of coolant. The coil tests fine. EGR is clean and tests fine. Any ideas where to look now? I'm hoping for something less than a new engine to fix but I'm pretty dicouraged at this point. Any help would be greatly appreciated.

A bad sparkplug wire will throw you a curve. It'll show spark but under compression, the resistance at the plug can have fire jumping an easier route.

Thanks for the quick reply.

I checked the wires on and off, in the dark running, and also with a water bottle and they looked fine. I also swapped wires with a spare set and still the same.

A bad sparkplug wire will throw you a curve. It'll show spark but under compression, the resistance at the plug can have fire jumping an easier route.
Chris has a good point. Try doing this. pull your #2 plug and swap it with one of your other cylinders and see if your trouble follows or just stays on #2. This way you'll know for sure if its the plugs or not. Make sure you take it out for a run and test it under load. Hope this helps.

ok, swapped plugs. Still on #2. Swapped wires. Still on #2. I'm out of ideas.

Wow, running out of options...
The star wheel pressed on the distributor shaft-under the rotor button, I think some call it a reluctor...is it cracked or a star broke off?

A compression test on #2 is next imo.

Wow, running out of options...
The star wheel pressed on the distributor shaft-under the rotor button, I think some call it a reluctor...is it cracked or a star broke off?

A compression test on #2 is next imo.
If the reluctor check OK, and your compression test is good. I like to sugest that there is a possiblity that your new fuel spider might have a pluged poppets. I just ran into this trouble with one of my cars. I had a P0300 which is a mulit Cylinder Misfire. After going through everything without any success. Here is what made me suspect it was the poppets. After running at idle for about 30mins. I pulled the plugs and found that 2 of the plugs where burning lean and the rest where burning normal. The lean plugs where on the same 2 cylinders that where coming up on the Multi misfire. I pulled the poppets out and cranked the motor and watched the fuel spary. Sure enough. my misfire cylinders was only trickleing fuel and the others were spraying normal. Replaced Fuel spider and motor ran like a champ. Being that your fuel spider is new. It should be under warrenty. If all fails, Try changing the fuel spider again.

Good call Gabe! A malfunctioning poppet is also described in the Service Manual.