P0125 is for your coolant system. It means your vehicle did not get to the operating temp in the given amount of time.

P0300 is engine misfire probably because of the engine not being up to operating temp.

P0420 is for your cat. It is being set probably because of the first one still. if your engine does not get up to operating temp then you will have a lack of emission efficiency. What i would do is get a coolant flush or a new thermostat if your old one is sticking open. maybe astro355 will chime in with more info.

 

Thanks!
I just ordered ignition parts(cap,rotor,sparkplug wire set and plugs) and a new thermostat from rockauto.com( I live in Sweden) and let us hope that it will solve my problems.

 

How many miles are on the van? Another common cause of the P-0300 is the distributor drive gear. When you're changing the rotor, try to turn it left to right and see if there's any slack in it. it shouldn't move, if it does, check the gear.