YOU WILL NOT see more performance with $400. It takes thousands to see a big difference!
although you could start with a CAI, kolak's exhaust, and a bored TB.
but since that would be over $700 right there, plus the installation of the exhaust: buy a used CAI, and piece together your own exhaust using a high flow cat FM muffler and a turndown after the muffler.
might as well sell it and get a V8. It gets the same mileage.
Not neccessarily true, as stated in an earlier post, the 1999 and newer 4.0 intake manifold is a great bang for the buck mod. There was a link to a thread posted here that had dyno sheets showing solid gains in HP. Considering that you can pick up the manifold for less than $100 at the boneyard, it is much more cost effective to start with that, then add a good free flowing exhaust and header to compliment the intake manifold.
Being that the OP's vehicle is a '95, he can also upgrade the factory ignition system with a high output coil, cap, rotor, and wires, of course he could go all out and get a performance distributor as well. With a healthier ignition setup, adding the '99 and up fuel injectors would be a good idea to, since they have a better spray pattern for improved atomization of the air/fuel mixture, this would allow him to create the most energy possible without having to add more fuel to the combustion chamber.
If the OP is creative enough, he could probably pickup the '99+ manifold, injectors, wires, cap, rotor, plugs and coil for under $400, add in a decent exhaust system (such as Kolak's) and he would be right around $700, assuming he doesn't have to pay for someone to install these items, that would net him noticeable increase in power for under $1k.