OK so handling or "drivability" is the way you want to go. I wouldn't go with a "tune" yet, you just haven't modified the engine enough to justify spending $400.00 or so on a tune.
What do you mean by "lowered" the car? Look into the SVT or Dynamic suspension system from Ford Racing. You can also get a sway bar set from them. A front Strut Bar will help the handling. You have a manual trans. so get a rear engine mount with urethane instead of rubber.
For a little more power and a cool sound an exhaust is a good idea. This will be the most expensive upgrade I've mentioned so far. Oh and re-gap your stock plugs to .060.
Look into Stainless Steel brake lines to firm up the feel of your brakes.
By this time you will have a pretty "funner" ride!
Color Matched Grill, Mid-Wing Spoiler, Clear Side Lights, Audiophile Sound System, Stealth CAI
, SVT Suspension and EAP wheels, FRPP Strut Tower Brace and STS.