when i purchased my 90 vert a year and a half ago my intentions was a nice driver with some go parts and some show parts.to this end i have assembled a decent engine with cobra upper and lower,edelbrock heads,exhaust,mass air,t/b,and a 5spd conversion.this took care of the go.(the 4.10's didnt hurt either).now when it came to show i installed bbk springs,now ditched for motorsport b springs,chrome cobra r's,saleen wing,cobra grille insert, and black interior.here is the problem.when i bought the car it had only 72,000 original miles.this car was extremely tight.no rattles or noises.now the car has 76,500 and it rattles,shakes,on some days it feels smooth on others it feels like a bowl of well you know.is this common am i crying the convertible blues.non of my hard tops had this problem.i have even installed a stut tower brace and double cross subframes.what gives.your advice is appreciated.