Hey,

I did some overhauling on my F150 but some problems remain.
Here's what I did:

- New headers (one manifold leaked before)
- New Denso Iridium Fine Wires
- New oil & filter
- New K&N cone filter
- New goodyear serpentine belt

As soon as I had the new headers bolted on I noticed a weird shake after the engine warmed up.
When I'm in Drive and step on the brakes there's some weird vibration for about 2-3seconds, it cannot say if it's always in the same time sequence.
I think that because the O2 sensor measured false data before the engine is running now on lower idle rpm and maybe therefore some of the engines vibration is transferred to the cabin?
But there's another thing that worries me. I was driving home today with the heater on, when I parked (motor running) to get something off the bed quickly I noticed the exhaust noise getting louder, I got back in and noticed some rpm increase every now and then (still in Park).
After I parked I switched the heater off and the lights to park lights and the rpm increases seemed to go away...
Before I did the tune-ups I noticed the inconsistent idle when I was sitting at a light and had the A/C running...

I'm really worried that I did something wrong during my tune-up modifications but I'm not sure what it could be... could the EGR be leaking?

Other than that the truck drivers perfectly fine, seems to have lots of power and starts up without a problem.

Any help is appreciated! Thank you guys in advance, Johannes