My car is doing the same thing. At 6k it breaks up, I'm boosting 8lbs on a non-seq set up. I have a reprogrammed ECU but not all the mods its tuned for. So I'm running very rich. I'm at about 12 miles to the gallon city just cruising. I'm just going to buy an AFC and head to the dyno and tune it. I'm asuming its breaking up because of too much fuel, but I'll find out for sure when its hooked up to the wide-band.

Don't know if it is related or not, but my car will studder and pop if I try to boost it with below 1/2 tank of gas. If I fill it up, it runs fine. My last FD did the same thing. The concensus is there may be a leak at the pump not letting it get fuel at lower levels while accelerating. I just always have 3/4 or more in my tank at all times to prevent blowing it up until it is resolved :).
Joe

do u guys know if a J&S ultra safeguard ignition control makes a difference? i bought my 94 FD with one installed and I currently have a DP and Apex GT catback and i don't have a boost controller and I boost to at least .8/.9 (greddy boost gauge) and i've been driving the car for 9 months now and i push it everyday and havent had any problems. I also have a wideband that came with the car but I've never hooked it up to see wat my afrs are.

is my motor in danger? last time i had a compression test was in feb and i had 7.5s on the first rotor and 7s on the second rotor.

How long are your spark plugs lasting? I am running just about the same setup as you and I'm fouling out plugs 100-200 miles...thing I'm pig rich and also might have an ignition problem...guess I wont know until I eliminate them one by one.

Put a digital volt meter on the 02 sensor keeping it connected to the ECU. Just tee in to it and ground the other side. Set it at "DC" volts at a low scale. I would use the 2 volt scale or "MV" Milli volts. The sensor will read between .1 one tenth of a volt to just over 1.0 volts.
Get it hooked up in the car and drive it where it acts up. This is to find out where your mixtures at. If it is reading below .9 or .90 or .900 depends on scale you have it on. I would be carefully. It "could" be too lean. If it reads .7 etc get off the gas now or apply for a loan. This is surely not the most accurate way to test the rich or leanness of the engine but can be helpful. I thoughts are its rich now that the exhaust flow has been slowed by the cat.

Try geting new injctors..

I do not know if you found out what was wrong, but I did not hear anyone suggest to chect the coils. I had a similar prob with mine and we changed to 2nd gen coils (they say there better) and changed the ignition to a MSD and it ran hard. well till I blw the seals but thats another story. Hey Im no mech. but try it may be worth a shot.

I replaced engine and got PFC. I have no more problems.

Amel

Sometimes when is a boost leak it don't apears in the boost gauge , meaby there is the problem , doble chech the boost houses and the blow off.