Idling problem when hot after rebuild engine

Hi every body!!

I have a 360 Challenge, the car got fire few month ago during testing on track. Some of the engine wiring was damage.

I replace all the engine wiring and sensor from a crash car. Same time since the engine was out of the chassis I decided to check the compression and leak down of the engine. The exaust valves was leaking 5-10% so I decided to rebuild the valves and replace the engine cam belt.
After rebuild I checked the valves clearance (camshaft support to valves) but was 0.100 to 0.060 mm bellow the mini. So I make the valves shorter to get the right values.

After reassemble every thing and start the engine the idling is not very good, very low and sound like sparking sometimes.
When engine is hot it cannot keep the idling. The spark plugs are all same , looks black.
I have check with SD3 but nothing wrong.

Someone have some ideas???