I've had my truck for about 7 months and I've replaced the fuel filter, spark plugs, cops, true duals with x-pipe, and cleaned the mass airflow sensor. I used seafoam threw the brake booster and it gave me a small tick and now when I got the pedal to the floor it will miss and finally today it threw a code p0305 I can't figure out what I need to replace to fix the miss and/or tick. It's a 07 fx4 with 73xxx thanks for any help

 

It doesn't always miss but when it does it misses hard for about 30sec then runs normal

 

Check the ignition coil again. What did the one in cylinder 5 look like? If you didn't blow it out with compressed air, there still may be moisture or debris in there and a new ignition coil won't help.

 

Does the misfire occur in a certain rpm range or around certain speeds? Or just anytime you punch it? Does it misfire in P/N when you rev it up? Are the replacement plugs and COPS motorcraft?

 

make sure you replace with the right ones . gasoline on the boots will ruin them , clean out the recesses, Use compressed air . make sure they are dry , use hair dryer. I have heard of antifreeze getting into there . Clean the spark plug porcelain , use special grease on boots but don't get it on metal parts . utube has video on applying non conducting grease on boots .

 

Drivers side front , you could swap it with 6 to see if its the cop and or boot .

 

if you are having a rough idle at low rpm(stop sign,etc) and are having a bump/shudder in at higher speeds(50mph+) check to see if its throwing a code for the throttle position sensor. It will run rough at low rpms and also at higher feel like a transmission is slipping/missing.

Also probably worth checking the condition of the FPDM located under the spare tire to see if it has any evidence of the notorious corrosion that is prevalent with these trucks.

Recently had a similar issue where mine was missing at low rpms and at highway speeds even though ive replaced coils, plugs, fuel filter, FPDM etc. Swapped out the throttle position sensor and has run like a top ever since

 

Thanks I'll try swapping them out but it did it with me last cop too and it seems like it does it after I get past 3500rpms but will keep doing it after it starts even when I let off then it will just go back to normal and they are accel cops and motor craft plugs

 

How hard is it to replace the fpdm and what is it would I notice easily if it's broken? Thanks

 

Never mind I've heard about that I'll check it and probably just replace it anyway