Help With 2.9 Running Rough

[RangerDanger12]

Hey guys, I could use some help diagnosing an engine problem with my 2.9 engine. This truck sat for 10+ years, so I've had to replace a lot on it. I've made good progress, but I just can't get the engine running right. It's running really rich and typically stumbles between 3 and 4 thousand RPM's (though usually only while driving, not idling). If I press the gas pedal down more, it picks up again. It seems to run better before it heats up and the problem gets worse the longer it is driven. It is overheating, but I'm assuming this is just because of the rich running condition. The problem is also a little bit inconsistent and it seems to go away for about a minute any time the truck is turned off then back on. For example, it kills itself while driving it sometimes. If I immediately start it back up, it runs better for about 30 seconds. I know it has an exhaust leak, but didn't think it was bad enough to cause this much of a problem.

So far I have replaced:

MAP sensor
O2 Sensor
Cap and Rotor
Ignition Wires
Ignition Coil
Spark Plugs
Temperature Sensor
Thermostat
Fuel Pump
Fuel Filter

The check engine light was on before replacing the temperature sensor. After replacing it, the light hasn't come back, but the problem is still there. I have also checked vacuum lines. I didn't see any obvious cracks or disconnects, but it's possible they're too small to see. I'll plan on fixing my exhaust leak, but I'm still waiting on parts. Any other suggestions for what I should check?

Here are a couple of videos of the truck running: The first one shows the problem when it is really acting up. The second video shows the truck running much better, but the problems came right after about a minute of driving it. Any suggestions you guys have would be awesome! I've enjoyed working on this truck, but I am definitely an amateur mechanic.

 

[SenorNoob]

Absolutely could be the exhaust leak if it's close enough to O2 sensor and large enough.

Running rich doesn't usually cause overheating. Leaner is hotter. Some race engines actually run rich to prevent overheating.

It sounds like it runs fine when the engine computer is in open loop then changes when it goes to closed loop. That would indicate a problem with the O2 sensor. Could be bad new sensor, bad wiring, exhaust leak, or even a capacitor in the PCM. You'll have to some testing to find out. Does it have any codes?

 

[RangerDanger12]

Thanks for the response.

Hopefully the overheating will be fixed by the thermostat replacement. I’m also planning to flush the coolant and replace the water pump.

I don’t know if it has any codes. I’ll have an OBD1 scanner on Monday and can check then. Is there any way to test if the new sensor is bad? Is there any other testing I can do that doesn’t require the scanner?

 

[SenorNoob]

A multimeter can kinda read the voltage of the O2 sensor. Not sure how useful that would be in this case...

How did you come to the conclusion it's running rich? Pulled the plugs?

 

[Terrys87]

The overheating could also be a really dirty cooling system. Pull the thermostat and run some cleaner in it for about 30 minutes and flush real well.

I am having some issues with mine and I had two mechanics to tell me to run Motorcraft spark plugs. I am swapping them out tomorrow and see if it makes a difference.

I would try another TPS sensor for your 3-4k rpm issue and see if anything changes.

 

[rusty ol ranger]

Hopefully it doesnt have a cracked head. 2.9s and heat dont mix