Car missfiring? Only 4 out of 6 cylinders are working?

I got a 2002 Ford Escape v6 and it had a low idle and would die also I was getting 14 mpg. So I looked up some stuff to fix it so I changed my spark plugs and cleaned my mass air flow sensor( with appropriate cleaner) after all of that I started the car and idle was rough so bad the car would shake it was even hard to start up so I swapped and put my old plugs back in and it still is running like this we figured it was the injectors used a set of tools and heard them firing. The coil packs still fire does anyone have any ideas what's going?

Did you put two of the spark plug wires back on the wrong spark plugs.

Maybe the timing belt has slipped some teeth.

No year, make or model, and you have no idea if it not sparking or it is lacking fuel. Clamp a spark plug to the block and put each plug wire on it to see if you have spark. If you do, you have a fuel problem.

When you pull the trouble codes, they will tell you which cylinders are misfiring. Those are where the problems are to focus your repair attention. There might be more than one trouble code.

You mixed up the plug wires or one coil isn't firing for some reason. You have three coils in that pack, each firing two cylinders.

The engine might have 2 bad ignition coil, blown head gasket or low compression engine