LC-1's can be very problematic.

Either throw a narrowband back in, or leave it unplugged and try it.

Although a description better than lumpy might help. Is it off cylinders ? At idle, or all the time ?
Will it drive ?

Have you checked the coils and plugs ? These can often be damaged when people are fitting plugs. Over time the coils can go brittle, and it doesnt take much to break them. People also lose the rubber insulating boots somehow, or damage them.

You wont be connecting a laptop up easily....unless you develop some software to do it lol.

But there are connectors under the dash that will flash any fault codes. Very easy to do, although if the CEL isnt on, then chances are things are ok.