When i bought car Alfa 156 2.0JTS(2002) had broken thermostat so most of the time temp of engine was around 50C. When I changed thermostat for new started problems with error P0301, but it was only when engine was cold and on idle rpm. When temperature pass 50C all back to normal or when i kept rpm over 1500. Last days i changed timing belt and exhaust camshaft, this problem become enjoying now misfire even around 80C or even on higher rpm. But when get around 90C again back to normal and engine have good power. The spark plugs are new and coils are good tested, i checked wires to coils till connection behind engine all is good. Do you have any ideas what can be broken and why is worse after replacement of timing belt. Sometimes stored errors are P0301, P1172 i know best would be change injector for test or or check its connection but how to get to it without unscrewing the intake collector?