[Thomas]

The other issue is I think is the muffler or cat clogged. It loses power when you shove it to the floor, and the rpms get above 4000 rpm. The shift point on these trucks when they’re on the floor is about 5000 rpm, so sometimes it just stays between 4-5000 rpm, and won’t shift up. My old truck (’97 chev) did the exact same thing because of a clogged cat.
So any guesses?

I also checked the fuel pressure today, key on it hits 60, and drops to 55 when the pump stops, it idles around 50 psi, and gets close the 60 when I rev it. 60 is what it’s supposed to be at, but my other truck ran fine on about the same pressure. I bought the truck a couple weeks ago, and the past owner says it has a new pump and filter.

So, any guesses? and Thanks for any help in advance.

And sorry for the long read, and the two posts, seemed easier to read and understand in two haha

[Thomas]

I’d try bleeding the brakes and see. I’m not sure if this is true or not, but I’ve heard the fluid level will go up when you squeeze the breaks if the seal inside the master cylinder is bad.

[Thomas]

I’d try bleeding the brakes and see. I’m not sure if this is true or not, but I’ve heard the fluid level will go up when you squeeze the breaks if the seal inside the master cylinder is bad.

[Thomas]

Vortec motor? I’ve got a ’98 GMC pickup with the 4.3 Vortec v6, with 348,000 km.

[Thomas]

Vortec motor? I’ve got a ’98 GMC pickup with the 4.3 Vortec v6, with 348,000 km.

[Author]

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