Mystery issue

[ProjectScath]

I have joined this forum for a friend because he has grown tired of dealing with the problems he is having and wants to sell his Explorer. But he has given me til November 10th to try and fix it. Here are the issues: very low power, to the point where after 20-30 minutes of driving it takes 15-20 seconds to get through an intersection at under 5 mph. If you rev it in park it will rev to about 4000 then start going back down slowly. It sounds like its missing and as very rough idle. We just replaced the coil, plugs, wires, tps, and maf sensor. Now for the details. It is a 1999 Ford Explorer with a 1996 4.0L v6 engine. The MAF that was on it was for a 1999 so it was replaced with one for a 96. He just had the flywheel replaced and swears all the problems started after the replacement but as I rode in the truck before the flywheel broke it had all the same issues. It seems as if the problem is worst after the engine is completely warmed up. I ran a live scanner on it while we drove it and found that the o2 sensors had odd readings: Bank 1 sensors 1 and 2 read 0 volts while Bank 2 sensor 1 was fluctuating wildly and Bank 2 Sensor 2 was stuck at 1.27 volts. It also threw a code for the Intake Air Temperature sensor but we could not find it. I really want to help him fix this but have no clue where to start. Any and all help would be greatly appreciated.

 

[DieselHilux]

Classic symptoms of plugged up cats, unbolt the exhaust at both the manifolds and take it for a (loud) testdrive.

 

[4rd4life]

Classic symptoms of plugged up cats, unbolt the exhaust at both the manifolds and take it for a (loud) testdrive.

x2 or if you cant take apart the flanges you can remove the o2 sensors. if its a clogged cat it should run better after doing one or the other

 

[ProjectScath]

Since it is a 96 engine, what would happen if he had the cats removed? And we had an exhaust shop test them, said they were fine.

 

[albi1cnobi1]

Here's something to look for. In 96 the intake air temp sensor is located in the intake tube about midway between the maf and the throttle body. On the 99 the IAT sensor is combined with the MAF sensor. Which harness are you using? If you're using the harness from the 96 you'll have to use the MAF and IAT sensor from the 96, as well as the intake tube from the 96. And that goes for the 99 harness as well, you have to match the sensors and intake tube. Both of these issues will give you the symptoms you're experiencing. Thats probably why you can't find the IAT sensor.