1998 Mitsubishi Galant • 17,000 miles

My car misfires when cold sometimes if its worm out it dont computor gave codes and I replaced idle air moter / throtel position censor and cheked for vacum leak with propane no leaks what could cause this im stuped
October 18, 2012.

What were the codes? We need them

i would start with plugs and wires/coils as they are the most common failure for miss fires


Oct 18, 2012.
The codes were po120 po300 po304 po505 a year ago I had to do a timing belt, balance belt, and put a new head on the engine which is a 2.4 sohc at that time I put wires, cap, rotor, plugs car ran great till three months ago it started to give these codes I changed the plugs again and put a k&n air filter in when it doesn't misfire it runs good only misfires at idle if u step the idle up for a while it goes away. When it gave po304 I switch #3 and #4 injector no diffrence still misses. When it gave po300 I put injector cleaner in 2 tanks of gas didn't help. The milege went from 30 to 27 miles per gallon. Did a compression check it was 180 on 3 &1 and 130 on 4&2 which is odd. Doesn't overheat uses little oil. Could it be something in the distributor because the coil and the advance is electronic and there part of the distributor. I don't know what to do at this point but drive it till it dies.

Oct 18, 2012.