I have a 96 1500 5.9, all of a sudden have no power, will get up to 50mph and the longer or hotter the engine gets the less power I have, sown to 20mph. Give it more gas and it get worse! Changed the plugs they look fine and the wires and cap and rotor, also changed the fuel pump, with no difference. Also disconnected the the exhaust with. At the manifold with no difference. Could it be a low voltage issue!?

 

So you had the exhaust completely removed and took it for drive and it did the same thing?

 

Yes, its a shop right now and that's what he is telling me!

 

Can they check your compression numbers?

 

When the engine is cool it runs better! But as it heats up the problem gets worse! When the exhaust was pulled from the manifolds yesterday they were just off to the side partially exposing the manifolds about 50%.

 

Disconnect front O2 sensor, take it for a drive, see if its any better.

 

Just curious, why did the shop pull the exhaust manifolds off? I've seen 02 sensor wires that would short out from heat and then be ok again after they cooled down. Idk