2.0 nissan serena running bad when warm?

I recently bought a serena that was making a funny noise and running bad i got it looked at and found out timing chain was damaged. I got that repaired but it was still running bad when it warmed up, since then i've had it plugged in by mechanic and looked at by auto electrican they have changed lamber sensor, coolant temp sensor and the cat and it still runs bad and cuts out when its warm. anyone have any ideas?