Alright so I'm new to this bit wanted to give it a shot and see if you guys can help me out. So I have a 2004 f150 5.4 3 valve 7lug heavy duty and just always seems when I got to replace one thing another occurs. So to start I replaced spark plugs and timing sensors on front of block and cleaned vct solenoid and cleaned throttle body, well anyways every morning get up and start it let it run 15mins er so and runs like a champ but once you get going and hit speeds 55 or over and come to a stop it wants to fall on its face. Then engine light starts flashing so plug the scanner in and this is what I get P1285,p0307, p0305 p0304, p0303 p0300 p0172 p0012 p1299 p0420 pp0340 p0316p0022 p0012 so then I cleared it and ran fine again until 55mph again and then popped P0012 P0022 P0300 P0303
P0304 P0316 P0340 P0420
P1299 P0174 P0606 P1286 so by now I'm completely lost so I cleared then again ran fine then it P0174 P0300 P0303 P0304
P0340 P0012 then wah bam again plugs done at 11/13 sensors throttle body and vct cleaned last week please help I'm stumped??? This is a problem that I always had since about 75kand now have 138k have to drive with overdrive off or else it free wheels after 2nd gear in less I hammer down on it but soon as I left off it revs up and free wheels

 

Have your catalytic converters checked.

 

No they have not been checked yet I could have them checked and see runs fine when I first start up and if I don't do over 55??

 

Is there any way to check them myself?

 

Yes , if your engine is like mine was , it won't rev over 4000 rpm.

unbolt cat (or cats) from manifold just so there is a gap , and if its your cats it will go right up to 5000 rpm , It might be wise to pay a muffler/cat mechanic to do this though.

There is a backpressure test they can do, but I have found it to not be as surefire as just un hooking them.