Speed density - how far can you go?

[302 LX Eric]

First, some background, then I'll get to my questions:

A friend of mine has an 87 GT (SD) with about 60,000 miles on the clock. We gave the car (stock as stock gets) a complete tune-up and it ran very well. Great throttle response and clicked off a 14.8 on street tires. Not too bad.

Then, we installed a Hurst shifter, March pullies, BBK shorty headers (1 5/8"), 2.5" H-pipe, and 3 chamber Flowmaster exhaust. We took the car back to the track where it ran a little better with a 14.6 on street tires.

Next, we installed a Trick Flow intake. Once we started it, blackish blue smoke billowed from the pipes and the fumes just about knocked us down. The idle was very erratic - from 600 to 2000 uncontrollable. After checking and re-checking everything we pulled the intake and put the stocker back on. Bing-bang-boom all problems solved. Idles great, no rich exhaust.

So, will the SD experts give an analysis of what happened - and why this simple intake change (70TB too) caused so many problems? And, what really puzzles me, is why some folks here on the Boards run all kinds of mods with SD with no issues, while others can't change a sparkplug without having driveability problems. Is it some sort of computer issue, or a case of mis-matched parts? I'm very curious.

Note that the parts were chosen based on the owner's future plans for the car, which include TFS heads, cam, converting to mass-air, etc.

Thanks in advance for the replies.
E