Egr/Hot engine compartment/tempurture gauge steady
 

Hey,
I bought a 1999 mazda b4000 4x4 152000miles. I have replaced the heads since 5/6 cylinders were cracked. My check engine light came on after we cleared the codes that the lack of pressure in the heads caused. The code indicates a bad egr valve we replaced the egr and the light stayed off once codes cleared. I drove the truck a few days and noticed the engine compartment was excessively hot. One catalytic converter hot and the other cold. I replaced it thinking clogged cat. Again issue solved, so I thought. Today check engine light comes on and engine compartment excessively hot. The oil looks clean but the coolant is dark and it looks like oil in the radiator. Someone help me before this turns into a money pit. Please. Egr code came back again.