Texas emmissions is easy to pass.. honestly my v6 passed and you can pass as long as your engine light is off and the moniters, but two, are ready. Sluggish acceleration is probably due to it is a 97.. v6.. producing a whopping 145hp from.factory. plus the missing cat.. does Not help. Lack of back pressue screws the v6 in the performance of the motor. I personally would, if you have the money, get a the cat fixed and get it plummed for dual exhaust. Flowmaster 50 series mufflers so it can sound simi stock. Unless you want it louder then go with the delta 40 series. Mid pipe doesnt matter just preference between h or x pipe. Transmission.. thats sketchy.. if the owner before you "fixed it up" then id probably change the filter and fluid with proper mercon V fluid. 14qts to fill it. If that doesnt help then id suggest you find a transmission guy to inspect it. The main seals... those are toast. Id service your transmission fluid the same time you do the rear main seal. Front seal youll need a harmonic balancer puller. Differential leak could be the rear cover gasket or possibly the front oring, I believe, leaking. If you also want a quick boost of HP out of that v6 change the upper and lower intake out to the 99-04 v6 mustang intakes. That should get you an estimated gain of 50hp. Suspension is fun to do on this car.. the rear shocks of course are butter.. tie rods are alright.. wheel bearing simple enough and the ball joint... ouch.. anything else you have questions about respond id love to hear how.. fun this car will be for you. hah good luck!