What should i tell Toyota to do??

Hey guys im taking my baby in for a new exhaust manifold gasket as i can hear the leak, and im going to ask Toyota to do some checking. Mine is a 97 4x4 2.7L 5speed and i have noticed a lack of power recently, granted its a 4cycle and im running 31X10.50s on steel rims but i feel it needs some tuning. she has about 150,000 miles on her with new plugs wires and coil packs. MAF cleaning? Check the Catalytic converter? Maybe time for a valve Adj? Help me out guys!

This is her....

 

My experience with your question is with a different vehicle. Though I had a serious lack of power and an exhaust noise which sounded like an exhaust manifold to me. It was the catalytic converter in my case. The sound was similar to this. Mine was much more clogged though.

http://www.youtube.com/watch?v=sPkfNqlCTQs

Your truck is beautiful.