No heat or very poor heat, the code said bad.

Don't know if htis is your problem with the code but here is a tip.
Had one come in for a p0128. Theres a rubber seal that tears along the sealing point for the t-stat, setting the code. I didnt have to remove or raise the upper intake. Take loose the throotle body with wiring still connected and the left t-body heater hose, lay it to the side. Next take loose the rubber coolant hose that connects to the front of the motor and runs along the valley of the intake. Take a good 12mm 1/4inch swivel and take loose the 4 t-stat bolts. (I also unplugged the coolant sensor and took loose the upper rad hose) Hold your mouth right, a few twists and turns and she comes out. Most folks know this trick, but putting the bolts back in the t-stat housing get you a piece of paper, lay it in the socket and press your bolt it there, it won't move.