Puzzling starting/idle problem

My car is a five-speed non-turbo. I am having some difficulty starting it as of late. It will crank and crank for fifteen to twenty seconds and finally start. Then if you are at idle it will occasionally die. While driving down the road I have no problems. Before this problem developed I had performed the following repairs. New plugs and wires, cold air intake, flow-master muffler, new alternator, new CV joints, new control arm, new sway bar bushings, new fuel pump assembly. I have a 180 degree thermostat, but have not added it to the car. I am still debating if I should. I bought a Diablo trinity performance programmer, but it does not work for my vehicle so I will be returning it. Are the problems I am having coming from my modifications? Do I need to get the car tuned to eliminate my hard starts and occasional loss of all power. When dies at idle or low rpm's it is just like everything shuts down goes off. Could it be the ECM?