Honestly: Check out Ebay. There are several 2nd gen's on there for a decent price and some really cheap 1st gens (yeah, some are cheap for a reason ~LOL~ but some seem to be in decent shape.) I was just cruising that last night.
I spent 3700 on mine, got a deal from a friend, and I have not been dissappointed at all. My '90 lists for almost 5k retail...but look around! Some are priced too high and there are deals if you look...but beware as I am sure you well know, deals can go both ways:bash:
I have a K&N drop in filter, it seems to help some (yeah, I know, there are some K&N bashing threads here, use what ya like!)
I am thinking of power mods myself, but not sue what else to do. Exhaust is usually a good idea, anything that lets the engine breathe better (my usual anolgy is clamp your hand over your mouth and go run around...see how much better it is when ya can breathe? Same with an engine!)
Ring and pinion swaps can be beneficial without messing with your engine, especially if you are running bigger tires, or just need it for a bit more off-road grunt.
Transfer case gear upgrades are great for off-road improvements if you don't need on-road mods.
For more road power, it all comes down to $$. Just about all of your "standard" engine tricks should work, from better oils and gear lubes up to a performance rebuild. There are folks here who can set you up with a 3.4L/supercharger swap, or just slap in a TRD 'huffer. If you want to go really nuts, there is always the GM small-block conversions (ick...I dunna like GM)
I may just be rambling (as I am trying to do this with my 2year old climbing me too) but hope I tossed something useable!