After installing a new engine in my subie I've been having problems with cylinder misfires ever since. I know it has been a common problem on the boards here but mostly with cars that are highly modified. My car is completely stock except for suspension mods. I'm constantly getting CELS for Cylinder misfire. There is always four codes when i get them checked, one for every cylinder. I took it to my local subie dealer one day because i was too busy to deal with it. They tried to tell me it was a problem with my ecu. Well they replaced the ecu under warranty and it did absolutely nothing for my problem. The other day i took a wild guess and replaced the spark plugs. Obviously this didn't work since it's on all four cylinders. That would mean that every spark plug was bad. This theory also makes me believe that it couldn't be the coil packs either. What's my next step to try to find this problem? It usually only does it at stop lights when it's cold out or the AC is on. It's getting really annoying having the car bucking wildly at stop lights. It also sometimes stumbles upon excellerating. Thanks for the help in advance. Let's beat the dealers at knowlege once again.