I have a 2003 explorer 4.0 v6 with about 85K on it. A couple of weeks ago I was on the freeway for about 30 miles and when I slowed down at a toll both my car would not accelerate. I pulled over and my car stalled. When I started it up again the idle was very rough and when I tried to accelerate the engine bogged down and stalled again. I was waiting for a tow and after about 20 minutes I started it again and it ran fine but the check engine light came on. I took it to the dealer and they told me the MAF sensor shorted out and the cats were clogged, and they wanted $1800 to repair it!! I replaced the MAF myself but I still have a CEL. Acceleration is OK from 0-50mph, but over 50mph acceleration is very very sluggish and the vehicle will not do over 70mph. Gas mileage is awful too. I drove around for about 30mins tonight and when I came to a stop idle was very rough and erractic and when I gave it a little gas it was better. How can I be sure this is due the cats? Is there anything else it could be or should check first? If it is the cats, where can I find a decent replacement part for this vehicle?

 

can be tons of things here is a list of some:
pcv valve
air filter
spark plugs
fuel pump
injector might have dirt in them


cats being clogged i doubt it at 85k miles those usually last lifetime and if they were clogged you wouldnt go anywhere because your engine wouldnt get any clean air because of the CO2 from the clogged cats.
your best bet is take it to a different dealer and have them scan check it---could also be your ecm