If it was running well beforehand, I'd recommend taking it back to the shop.

 

 

Safe to assume that you already made sure all plug wires where as they should be, none of the pulled off the plug? especially those at the rear of the engine where they'd work getting at bell housing bolts etc.

 

 

Dead miss as you seem to describe is ignition and or fuel related, nothing any "sensor" is going to cause.

It ran fine no miss before its last service that you've outlined strongly suggests ignition problem, a plug wire off or part way off or a damaged wire. Perhaps a plug with cracked porcelain insulator.

Getting to exhaust bolts bell housing bolts etc etc can tend to get rough on plug wires if not paying attention to em. Prying with bars sections of wood etc etc trying to line up the trans going back in etc. I have no idea what equipment they had on hand to do the work, would like to think a trans jack and it slid out and back in like butter but not always so. Skill level comes into play big time too how well that part went.

 

 

If they replaced the flywheel hope they used the right one. Also check for wires that might have gotten pinched between bell housing and block.