That ignition system fires 2 cylinders at the same time.
The spark goes from the coil to one plug, over to the next plug
through ground and then back to the coil to complete the circuit.
[ Series circuit. Called wasted spark ignition- that is why there are 3 coils.]
So if he did not check the plugs and you have a fouled one, the second one will not fire. A simple plug check will tell.
The second guess is the boot that goes to the plug under the coil tower. Ask if he changed this when changing the coil.