It sounds like a possible misfire under high load. It's impossible to just guess at so after starting it up and driving it a bit I would then park it and do the KOEO self test, count the flashes, and then find out what the trouble code is that comes up if any. This will let you know what the basic nature of the problem is. If you have an OBD 1 capable scanner it would make it easier.
You can do some basic things like changing the fuel filter, air filter, cleaning the MAF with specific MAF cleaner, cleaning the TB and IAC, and checking the condition of the plugs, cap, and rotor. Also look over the PCV piping and vacuum lines for any cracks or breaks. I would get a fuel pressure gauge to put on the Schrader valve on the fuel rail to test the fuel pressure too.