Allinkdupp

Thanks, I'll check that out too!

Allinkdupp

Would plugged cats do this only at high speeds. Hills ect?? How do I check em?

BuYA

I am having a similar issue. All started after my mech changed the passenger side valve cover seal because of a oil leak. Took it back and he changed 2 coils. Got it back and it's happening at 45-52mph. Going to change the coils 1 and 2 next. Also will check the cats. Will be reading for more info. Good luck

screw05

I used to have a similar problem, when I would floor it it would surge/ miss but only when it was floored. I had a p0171 code come up. My mechanic changed my passenger exhaust manifold gasket and no longer have that problem.

05jakev

I dont think this would be a go to way of testing but this is how I came to check mine. First was low power, I would come to some hills and the truck would have to downshift some times twice to get up the hill. Next was downshifting into 2ed to pass cars. Also could hear some pinging from motor when it was under load, and that seemed like all the time. Next was using a code scaner that can read live data I was looking at the engine load % and it was at 85% going 55mph and if I hit a small hill or just tapped the gas it would go to 100%. Then I checked the intake vac, it was normal at idle but just just driving it dropped to nearly 5" and just hitting the gas put it at 0". On my other truck a 98 dodge ram the hvac and 4x4 was all off vac and my hvac controls would just change on there own due to low vac when the cats went bad and the same happened with my aunts 04 jeep so I have had some experience when it come to bad cats. Last thing I did was I drilled a small hole in the exhaust before and after the cats. Started the truck and watched there the dust went flying cus of all the pressure in the system befor the cats and nothing after. And the last thing I did after I put all this together was to cut the cats open, smash the honeycomb and look at the leading edge of it and see all the holes were nearly covered with a white covering. Dont know what it was just know it blocks the air flow through the honeycomb. Welded it back together and now the truck sounds a bit different but have lots of power now

Allinkdupp

Update.... After a lot of test driving and a lot of research, I'm on the hunt for a bad cop tonight.

Dozer5

This was my exact symptoms from about 45000 miles to 75000. Only when on the gas at higher rpms. It eventually got worse. Changed the plugs and I haven't had it happen since.

Allinkdupp

Not the cops, not tranny fluid, not fuel filter, haven't pulled the plugs yet but I pulled cops 1by1 and there was a noticeable change in idle at all plugs... Any more ideas or should I just change the plugs... They only have 40k on them?

Allinkdupp

Just threw a p0300 random misfire code, it's going to the shop then getting traded in for a '12 ecoboost! I'm sick of the repairs on this damn thing!

Allinkdupp

Figured it out!