I have: 2001 Ford E250 4.2L V6 Cargo Van with 186K miles.

Recent work: New Fuel pump assembly, Fuel Filter, Camshaft Position Sensor, replaced all rubber hoses from vapor canister to the the DFE, New NGK spark plugs, New Brake Pads.

After I bought it sat for a year in the yard occasionally starting it once month for 15 minutes but never drove it.

3 Months ago i replaced brake pads and one brake line front passenger side. Went to bleed brake lines and it would not start. Discovered while trying to get it to start i burned up fuel pump on a empty tank of gas. I had a faulty fuel gauge reading a 1/4 tank of gas when it was empty.

Last month replaced Fuel pump assembly and new filter and now get 40 PSI on fuel rail schrader valve and starts. Idled good but could hear it misfiring with no code. Pulled plugs and saw two plugs were in bad shape with half of the hook where the spark ignites appeared to have been melted or welded away. Replaced with the Motorcraft ones with NGK ones that look identical. The misfire went away and idled (purred) like a kitten. Test drove it and while idling she rolled out of my long driveway with no problems, once accelerate all kinds of lose of power, spitting, and sputtering under normal accelerating condition with a obvious backfire only while accelerating not idling. It took WOT to get it to only accelerate normally. After 10 miles the code P0340 (Camshaft Position Sensor Circuit Malfunction) popped up on the MIL along with P0102 (MAF Low Input). I cleaned MAF checked (visually) for leaks, clean standard non oiled air filter good reassembled. I also replaced the CAM sensor (the Synchronizer looked intact with no play). Again started and idled fine. Backfire is now gone but still is gutless, sputtering when i give it gas with little power. After 10 more miles driving roughly 45 under those conditions I get home run the pocket scan tool with the exact same two codes (P0340 & P0102) but now these two are pending, and 4 new codes appear P0135, P0141, P0155 & P0161 =HO2 Sensor Heater Circuits. I checked the voltage at each Ho2 sensor on the two white wires at the harness and getting 11.49 Volts. While i am thinking about it i did not check for continuity or resistance of the sensors because what are the odds of all 4 sensors going bad? I will check it anyway shortly just to cross the T's and Dot the I's so to speak.
Is there anything that i am missing here?
Could both of my Cats be clogged up?
Can i just disconnect them and drive down the road to see if my power comes back? Will that hurt anything?

 

Update...
1) I verified my MAF is broke where the front resistor is soldered to the probe. Darnit! Will that cause a huge loss of power? The back resistor still looks intact so does the temperature one looks good.

2) I also verified all 4 Ho2s have continuity of 4.5 ohms on the white wires & as previously mentioned have 11.49V from PCM. Why in the hello is the PCM sending codes saying otherwise? GRRRR

Going to disconnect the Cats tomorrow to see if my loss of power returns. I'll keep you guys posted.

 

Update #2...
I disconnected the pipes from the headers and snapped one stud in half! CRAP! Made about a 2 inch gap between pipes and headers and went for a test drive. Word of advice for people trying this is to wear ear muffs. OMG was it loud and flames were shooting out of the headers! My Van was a 6 cylinder monster truck with all it's power back! Well the little power you would expect from a 4.2L. Anywho... I believe i found my problem... clogged catalytic converters!

Luckily for me i live in a area were no emission testing is done. So to get me by until i can afford to replace them gonna punch out the inside. This is going to be difficult because it is stock with two resonators before the cats with bends in the pipes that will make it difficult to near impossible without cutting it out! FYI, I don't have welding machine to do it right if i cut the pipes! IDK... I might just be forces to buy the whole getty up for both banks! GRRRRR!

 

Well, I removed my Harmonic Balancer and noticed the rubber had began to separate very little, roughly 1-2 mm. The key way slot on balancer and the camshaft looked like new. No play at all. Took no chances and ordered a new one none the less and installed it yesterday. It does not run perfect, but i do notice a slight improvement. I still waiting for my new Mass Airflow Sensor to arrive from china. They sent me a empty box the first time! It is scheduled to arrive tomorrow. If that sensor don't fix the last issues,,, I will then be leaning toward the EGR ports in the lower intake manifold to be clogged like in the following video.


I also have not checked all of my injectors to see if they are clogged either. But this video seems to be how my new symptoms are.

I will keep you posted as I swap damn parts until i find the broken one. LOL They were all broke to begin with and needed replacement. I bought new plugs and wires so i know that is not my issue, but may be one for another!