03 impala misfiring problem

i am having a misfiring problem on my impala it just started it has 6 month old plugs and wires been fine since replacing them the check engine light started flashing and it idle rough and runs rough here is a list of what we tried today it says cylinder 1 is misfiring we checked the coil , ignition module the map sensor but the only thing with that is that when we applied vacuum to test it it leaks vacuum. we cleaned the injectors tested the fuel pressure, even changed the coil it helped for a few minutes and then it started missing again so basically6 we are out of ideas what to try one other thing but not sure if it has anything to do with the problem the motor has been running hotter than normal but hasnt gotten to the point of overheating so if there is anyone that is very knowledgeable in this area please please reply we are stumped also thhis car has some ongoing electrical problems but dont think they apply to this problem please help the man who helped me today is a very knowledgeable man on vehicles and maintenance on anything since he has been in maintenance field for many years please help thank you for any and all responses

does it run better at higher rpm. if so check that vac leak. It will make it run hotter also because it it giving it more gas to cope for the extra air. A flashing check engine light says major miss fire. It is odd that it is just cyl1 miss fire.

does it run better at higher rpm. if so check that vac leak. It will make it run hotter also because it it giving it more gas to cope for the extra fuel. A flashing check engine light says major miss fire. It is odd that it is just cyl1 miss fire.
yes it seems to run better at higher rpm the vacuum leak is on the map sensor so i will get one of them and see what that does thank you so much when we took it in to test it the new one testes the exact same as far as dc voltage as the one that was and still is on the car but the one on the car leaks the vac. and it said in the instructions there should be a change in volts of at least one volt and both were exactly the same so i didnt buy the new one thank you so much

Make sure #1 has good compresion, look at the plug see if it is discolored. How did you clean the injectors?