Engine low power

1995 CHEVROLET 2500
150,000 MILES • 7.4L • V8 • 4WD • AUTOMATIC
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TOPHER SAVERANCE
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My truck does not want to shift to third or overdrive gear. when I give it gas it wants to bog down and does not get over 20 mph.
Jan 12, 2019 at 10:49 AM
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STRAILER
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Hello,

It sounds like you have a plugged catalytic converter. but to be sure here is a guide to help us check:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.
Jan 13, 2019 at 11:08 AM
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TOPHER SAVERANCE
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Thank you. I didn't think of that. but here is another question why would my truck not shift into third or over drive gear? I replaced the shift sensor would the catalytic converter cause that problem too?
Jan 14, 2019 at 12:49 AM
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STRAILER
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Sorry, I should have explained it better. With a clogged catalytic converter it lowers the vacuum so the computer think the truck is under extreme load which backs the shift points up. Please run down the guide to see if that helps. I would disconnect the exhaust and drive it to see how the power and shift point change.
Jan 14, 2019 at 9:34 AM
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TOPHER SAVERANCE
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Okay, I'll try it.
Jan 14, 2019 at 10:07 AM
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What if I run it to red line and then it still does not want to shift?
Jan 14, 2019 at 10:28 AM
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STRAILER
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Did you have the exhaust disconnected? If so lets run the codes to see what come up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.
Jan 15, 2019 at 10:10 AM