Late modle Advance Curve Kit

I have a 1989 Dakota SE with the 3.9 v6. It came from the dealer with a distributor advance curve kit installed. The kit was removed in 1998. The timing was set close to TDC. Recently, while overhauling the emission system, I changed the timing back to the original specs found under the hood (10* front of TDC at 2200 RPM), but I did not install a new Curve Kit. The problem is that I am not really enthused with the trucks performance or gas mileage - I wonder if an improved timing setting would help.
Question: Do the manufacture specs for idle speed and timing stay the same without the advance curve kit?