heres one for ya..i drive a 1500 with a 3.9l have already installed jet underdriven pullys, 180 therm,k&n 14in air intake,and went to electric fans.and dual chamber flow cat back exaust.ok now my question what can i do to get more noticable power out of this lill moter with out breaking the bank.i bought this truck with gas mileage in mind but lil did i know at the time the v8 offerd around the same mpg.(give or take a mpg or two).with much more power.now idk if what i did even made much increese but its done now.so any help would be very inspireing

 

High flow catalytic converter might help a bit.

The Fastman's TB might help you a bit too.
http://www.thefastman.com/Throttlebodies39.asp

Otherwise, your best bet may be to just save up, and then sell the truck and get one with the 5.2 or 5.9. Or do a V8 conversion.