I had some work done to the car and unable to take advantage of the upgrades I have done as the car had a ping under load, would start up crisp, and had a slight stumble. I checked timing and it appeared dead on. Currently I have 2 problems, the car has a severe stumble (can't figure out the cause) and stalls and running rough with backfiring after pulling the waterpump, crank pulley and opti to inspect timing and looked on. Because I didn't put new gears in when I did the cam install (122k miles) I put new ones in this time.
Started up the car.
Sounded great, with perfect idle until a minute or two later then she would stumble and die. Start it back up and the same thing.
If I kept the idle up she would die.
The backfiring and rought idle might be plug wires swapped in wrong place (will check that tommorow).
No codes being thrown, and the scanner show 108 (which means the computer is leaning the mixture) and the fuel pressure read 41psi and dropped to 36psi when revving the motor mid to high rpms.

 

Make sure the wires are where they are supposed to be, and make sure they are on the plug all the way. Could also be the opticrap dying as well...My car did the same things, and I checked everything, then it ended up being the mass air sensor, just some ideas

 

If your stumbling AND backfiring, that's a good indication of running lean. I would check fuel pressure at the running speed where the problem occurs. If you don't have a fuel pressure gage, they have them at Sears for 39.00.

 

Well after a few weeks of aggraviation, I think I have everything sorted out and should be able to see what my car can do with the recent upgrades.
The most recent problem was swapped plug wires on the opti.
Had number 6 swapped with number 8.
Started it up last night and she never sounded sweeter!
Going to take it for spin hopefully tonight and report back.

 

I'm having the same exact problem with mine what kind of heads, and cam did you use. And if you figure it out let me know. If I figure it out I'll post it back up. Thanks