hi all i have a ef fairmont i have recently replaced the exhaust on due to it was rusted out and with holes when i got the car now after replacing the exhaust a few weeks later it started missing and the other day i took the battery out and put it back in and started it and the miss went away and now its still there gets better once its warmed up any ideas would be great im going to get new leads and plugs but want to see if there is anything else i should be looking at i pulled the first sparky lead off the first spark plug and the car idle the same with or without the lead im hoping its a lead or coil pack

vaccum leaks. I say this as the headers might be running hotter now introducing excess heat to vac lines (booster) making them split or crack