I can tell you how to gain a few HP, but I dont know if you can get up to 100 without spending some money. If a chip is too expensive, then you probably dont have enough to put on a new exhaust or intake. Besides, chips wont help that much in such an old car, most of that stuff can be done mechanically. You have probably read that chips advance your ignition timing so you have to use 93 fuel. Well, in 91 and older tauri, you can do this mechanically. If you need detailed instructions, respond to this post and I will tell you. You can also remove your intake silencer box. I did that to my car and I believe I gained about 10 hp. If you really want to gain some power, advance you timing all the way, use premium fuel, and then dump about 2 bottles of octane booster into your tank. You might make 20 hp doing that.
Your tranny can probably handle about 160 hp, so dont discount forced induction yet, but thats really expensive.