You will always be susceptible to issues, the cars are around/over 20 years old.
There are many who map the std ecu's you have, but just try to stay off boost as said, otherwise you might be carrying your engine in a bucket by the time you get to msd!!
From your description it needs looking at totally from scatch, no doubt it will be silly little things that need seeing to, and hopefully not that expensive.
In the meantime I would check all the basics, ie sensor gaps, plugs, cam timing, boost leaks etc.
tabetha