Check Injection, Emission, ESP

Hi All.
I was wondering if anyone could help. The other day my 197 58 reg with 110k miles started acting up. I was doing 70 when i noticed a power loss and the engine symbol started flashing, i slowed down and then check emissions was displayed followed by check injection, these stayed on for a few minutes and then check ESP came on with the spanner. When check injection came on it ran terribly but stopping and restarting engine made it run better. Plugging OBD reader in brought up 300 and 325 which are multiple cylinder misfire and knock sensor, these both cleared with a reset but car still running lousy but now no error codes or dash warnings showing. I didn't replace the knock sensor as was told this wouldn't cause this problem. The AA took a look, he replaced all coil packs in turn and changed the MAP sensor, still the same problem though, it has been in a garage today and they are struggling finding the problem, it is running like a bag of **** and any help would be appreciated.;/

cheers