I have the 3.0 in my 03. Its nearly impossible to blow it up since the whole thing is cast iron, hence the nickname "Vulcan". For my first real car it had the power I needed. Mine was stock rated at 155hp and 183ft/lbs or somewhere around there.
Since then I have put in the MAC Performance intake and Flowmaster Super 44. The intake let it breathe and throttle response and mpg improved. Got a good amount of power out of it too. When I did my flowmaster I did a side exhaust right before the rear tire so I lost a ton of backpressure. That caused me to get not so great mpg, loss some low-end torque, but it was finally able to move air faster through the system and gained power and hp.
Do not get the chip or programmer until you have done other things to it. You will just have to reprogram later on and waste money. For example, my truck fuel mapping is off for the new parts so I plan on getting the screaming demon coil pack with better plug wires before I buy the programmer. My local dyno show estimates that after those 4 performance parts he can get me to around 225hp or so with a ton of torque depending on the tune.
The best mod for the 3.0 to put on to increased power without needing a retune is the Underdog-Performance 4-piece Underdrive Pulley Kit. It is a straight forward instillaton, adds some color to the engine, and is rated at 8-hp and 11-tq gain. For $199.99 its the best bang for buck in the 3.0L performance market. I plan to do the kit after my retune.
Hope my ranting helps any.
2003 Ford Ranger Edge 3.0L Vulcan Auto Tranny
MAC Performance Ram Air Intake
Flowmaster Super 44 w/ tailpipe before the wheel
Interior and Exterior LED w/ music interface
Ford Racing front and rear Sway Bars
Limited Slip with 4.10 gears