my first toyota

I just bought a 2001 Tacoma prerunner sr5
2.7 lliter automatic with 375,400 miles on it. It had been sitting since Dec. When the owner had removed the head to replace the head gasket. He recently purchased a complete head and head gasket set. I bought the truck as is and put it together myself. It would seem the gasket set was for the non-california emissions model.I got it put together and it runs smooth enough but idles at between 1200 to 1500
It also seems to be low on power when you stomp on it. I need to read the trouble codes and see whats up.

 

Welcome to TW! That is a lot of miles. You may have to bore the cylinders, and get new pistons, rings, bearings, seals, ect. Basically rebuild it. Good luck.