Well, my 1997 T-bird idles,drives, and revs up fine about 95% of the time now that I have the pi intake manifold installed. Other mods are: cotton gauze air cleaner, removed intake restriction,MSD plug wires,new platinum plugs,C&L 73mm maf body, and a cat-back Dynomax exhaust system. The car ran great before the pi intake swap (7.4 sec 0-60). It feels more powerful now, but the pleasure is tempered by a strange periodic idle and low speed misfire. It comes and goes for no apparent reasons I have been able to find. The idle misfire noticably can be felt, and results in a slower rougher idle. Giving it throttle only makes a higher speed miss, but it cleans up at large throttle openings. I can drive city stop and go for miles and miles, then suddenly the next stop will be a light bucking sensation with a noticeable miss through 1500 rpm. A few minutes later it can be all gone. So far, every time I get to my driveway, it's on good behavior and I cannot look for the trouble. I may be forced to field check it. I have put some alky in the tank in case it was water in the gas without a change. I have driven with the egr disconnected without a change (I have put a tube on the egr to vacuum check it as good). The symptoms are as if it is a periodic vacuum leak, but who's ever heard of a vacuum leak coming on periodically? If it were the ignition, it should have misfired at higher rpm's as well as idle and off idle, don't you think? Also, if there is a pi manifold related coolant leak, which I most likely don't have, wouldn't it leak out of the engine as opposed to into a port, since the gaskets are pi-type and completely encircle each port? I have checked most but not all of my vacuum lines without finding anything yet. Anyway, I am stumped again! Can somebody give me some possibles? thanks!