I have a 1997 Dodge Ram 1500 4x4 with a 5.2 318ci, it has an issue where randomly it almost stalls out and bucks and jerks at steady speeds until it's driven for more than 45 minutes than it'll be fine until it fully cools down again shifts fine thru all the gears does it with o/d on or off. I've replaced the iac-idle air control valve. Tps- throttle position sensor. Map-manifold absolute pressure sensor. Ignition coil plugs wires cap and rotor. No vacuum leaks I'm lost any help would be appreciated.

 

Sounds like a problem when it goes into closed-loop mode. Try unplugging the pre-cat O2 sensor wire and driving it around.

 

How many miles on it? Any codes?

 

About 195,xxx and no active or pending codes. I did try disconnecting the 02 sensor as suggested and ran it to town and back 68 minute drive. No difference.

 

failing cam or crank sensor, or possibly PCM. That one is gonna be fun to find.

 

But if the cam or crank shaft sensors are causing it wouldn't the check engine light come on? And how can I test those three things to find out?

 

The computer can't really tell if the sensor is really failing... it can only take a guess. If it is only missing one or two cylinders every now and then, it won't set a code. Even when it does, the cam/crank sensors share the same code......

The average home mechanic doesn't have the necessary equipment to test them though. Need an oscilloscope, or, the nifty-neato mega-dollar scanner that the dealers have.

 

Well I'll get it into a shop as soon as I can and post what they find so maybe it'll help someone else someday. Thank you all for the help and advice I always can count on good advice on here.

 

How is your fuel pressure?

 

Never thought to check it, but I don't have a test port on the fuel rail so how would I go about testing it?