Ford fiesta - P0103 with freeze frame P0304

Ford fiesta 2004 1.4 manual 40000 miles. Has very stuttery engine. P0103 logged as a fault code and shows P0304 in the freeze frame data. Has a TMAP sensor rather than a MAF sensor, Replacing the TMAP sensor has made no difference. Spark plug and HT lead to cylinder 4 seem fine. Someone has suggested it could be the coil pack causing the misfire but not sure whether misfire causing MAF problem or MAF Problem causing misfire?

Can anyone offer any advice?

There's a TSB out on some ford engines for a cracked intake runner. Check ignition system integrity and fuel delivery to number 4 cylinder. If all are OK and there's a miss, inspect the number 4 intake runner for a crack near the vacuum distribution block for the brake booster hose.
There's also a TSB on some FOrd engines for sticking valves causeing this P0304 code. You may want to check that out by calling dealer and getting the TSBs for that particular car.
As far as P0103, check for any restrictions in the MAF body. Check for anytime the signal wire is shorted to 12 V. Could be a bad sensor, but will need verification first.