Peerless Gas Boiler, Multiple Ignitions/Short Cycling.

I have an older Peerless Gas atmospheric boiler(1986 is the year of the boiler), it has electronic ignition.  The problem I have been having is that the boiler ignites several times before staying lit (this happens more when the boiler has not been run in >30min).  The boiler will get a call for heat, ignite the burners and after about 2-3 seconds will shut down and then do the same thing 1 or 2 more times before it stays lit(due to the multiple quick on/off cycles I get a noticeable gas smell for a few minutes around the boiler).   Any suggestions on what is wrong w/ the unit or how to troubleshoot?  I had 1 plumber in, and he was no help. 



On a second topic, I am leaning towards replacing the boiler with a Triangle Tube Prestige w/ hot water storage tank, or a TT Excellence..  My question is, for a 4br, 2.5 bath house is the Excellence hot water capacity enough?  We also have a large soaking Tub...I have heard that they are not the best for houses over 2bath or that have multiple hot water demands a one time(washer/dishwasher/shower)..anyone have any experience with the Excellence hot water production?