Dodge Performance Chip

I am thinking about buying a performance chip for my 1998 Dodge Ram 4x4, 5.2 L. I understand that it just plugs in to the OBD port. What I'd like to know from any of you who have tried this for your truck...>Does it actually improve horse power and fuel economy? > Once I plug into the OBD port, what I don't know is do I have to leave it plugged in permanently or does the computer programmed it once so I can take off in case engine light comes on? I've never tried this before but if it helps in towing or pulling a bigger rv trailer, I'll go for it. Appreciate any replies, tips, and/or information you provide.

Have good Ram days,
jomo17