Not 100% sure where they are located on an xr3i but if you look at the link I posted it looks exactly like the part pictured. it has a 2 pin plug and 2 fuel lines going to it. it will be bolted to something on the engine so it can react to temperature.

yea the adjustment of the screw won't help either, you may get it to run but once you replace the warm up reg it will be away to pot and will need set up anyway.

There is a company down south that refurbishes these warm up regs, I forget their name however sure a google search would reveal.