Some smoke off idle is normal on my '99 - works real good for the a$$ that just cut you off... grab 5th gear and floor it while the ehaust pipe is well positioned.
Mine has never put me in limp mode, I'd check you connections to the VP. I heard that the newer VA boxes connected to the MAP sensor also. Does yours? Mine does not. The PE box I had connected to the MAP sensor and would set the "Check Engine" light off every time I got into the throttle too much. If checking the connections proves fruitless, removed the VA and plug everything back in as normal. If the check engine light doesnt go out, remove the battery cables for a couple of minutes (A mechanic friend told me to do this, though I'm unsure if it works). Hook them back up, and if the check engine light stay on still, the code will have to be read and reset using a scan tool.
Good Luck!