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Discussion Starter #1
I recently purchased a used 2005 Suburban 1500 with 75,000 miles and has a 5.3 V8 Vortec engine. The other morning when it was cold, we started the car and it was running rough. The service light came on the car died a few times when it stopped. We checked the error codes and saw Mass Air Flow and Misfire. We replaced the Mass Air Flow, cleaned out the Throttle body, replaced spark plugs and wires, put fuel injector cleaner and dry gas to see if that would work. Still it is running and idling rough. Any suggestions? I've read it could be intake gasket, and about to replace the fuel injectors - but would like feedback.
 

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I recently purchased a used 2005 Suburban 1500 with 5.3 V8 Vortec engine. The other morning when it was cold, we started the car and it was running rough. The service light came on the car died a few times when it stopped. We checked the error codes and saw Mass Air Flow and Misfire. We replaced the Mass Air Flow, cleaned out the Throttle body, replaced spark plugs and wires, put fuel injector cleaner and dry gas to see if that would work. Still it is running and idling rough. Any suggestions? I've read it could be intake gasket, and about to replace the fuel injectors - but would like feedback.
Check fuel pressure first
 

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05 probably wont have a fuel filter. Id check the fuel pressure...should be around 55-60psi and if that checks out, get some intake manifold gaskets...its VERY easy fix
 

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Discussion Starter #5
Ok - checked out the fuel pressure and running around 60 psi. Ran the car this morning, it's running great on the highway, shifting well, no problems. As soon as I stop at a light, it drops to 500 RPM, and feels like it wants to stall. I purchased some brake fluid and sprayed on the intake gasket to see if that would even out the idle, but it didn't. Should I still replace? Any other suggestions?
 

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did u check the psi cold @ idle or hot @ idle? Pump might be getting weaker as it warms up.

gaskets are only $40ish for felpros and that's all you need.

by any chance have you removed the battery lately? You can have a rough idle after removing the battery. What codes did you get when you scanned it?
 

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Discussion Starter #7
Checked the psi at warm. Ran it for about 45 minutes and checked it when it is was at 60 psi.

I will replace gasket tonight and see if that works. I did spray with brake fluid to see if the idle would smooth out, but it still ran rough.

Just purchased the truck 2 weeks ago. Have not checked/replaced the battery yet.

Codes we are getting are P0300 (random misfire) and P0101 (Mass Air Flow) which we just replaced and cleaned out the throttle body. We also checked all vacuum lines which are fine.
 

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Checked the psi at warm. Ran it for about 45 minutes and checked it when it is was at 60 psi.

I will replace gasket tonight and see if that works. I did spray with brake fluid to see if the idle would smooth out, but it still ran rough.

Just purchased the truck 2 weeks ago. Have not checked/replaced the battery yet.

Codes we are getting are P0300 (random misfire) and P0101 (Mass Air Flow) which we just replaced and cleaned out the throttle body. We also checked all vacuum lines which are fine.
have you cleared the codes since you replaced the MAF?
 

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Check the coil packs.
 

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^thats what it was for me
 

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Discussion Starter #12
We finally figured it out. The catalytic converter had a bad valve spring. Had to bring it to the Chevy dealer and took 4 guys and three days to figure it out. $400 later and the car is running like brand new.
 

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What the hell is a cat valve spring?
 

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Lol
 
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