1Bad93Z

I have a problem and was gonna try to pick some of your brains to maybe point me in a direction. I obviously have something failing somewhere, I picked this car up a few weeks back from a guy on Craigslist. Great car for being a 93, Lots of things done to it and I'm finding more each day that is modded. As great as that is its also a problem...being fairly new to the LT1, I'm not really sure what to look for when I have some problems...So here's my problem, and its completely random, I have what seems to be a miss or a stumble or something its really hard to describe, but basically the car can be running just fine and then it gets this miss. Also with this miss my check engine, rpm gauge, and speedometer gauge all fluctuate and drop with the miss. The car stumbles all three of those flash and the 2 gauges both drop with each other and straighten out when it stops. The car also wants to die if I slow down enough. That may make no sense...The engine was rebuilt 11,000 miles ago and has many after market parts installed. Sorry for the life story, If you need any info I can always dig through the packets of paperwork he provided with the car for part information.