03 5.3 vortec Tahoe w/ 280,000 miles rough idle

[BIGDDADDI]

Ok [emoji108]ive changed complete the throttlebody with TPS, sparkplugs and wires, Fuel filter, oil sending unit , knock sensors, air filter, and Cleaned the Mass air flow sensor but at idle it still fluctuates between 600 and 400 rpms. Put it in gear and will pull and shift in to 2nd gear at like 20mph without touching the gas pedal. Engine code reafs its running lean in spots. Any suggestions on fixing this problem? Your help iys appreciated .

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[Scottydoggs]

busted vac line or vac leak somewhere will cause that surging. if it sounds like you installed a large cam surge, its a large leak.

 

[Doubeleive]

if the maf is original it could be part of the problem, I would swap it out just to see if it makes any difference, even if you cleaned it then it could still be bad

 

[SnowDrifter]

Car accelerates and shifts on its own

Lean code

Sounds like a pretty standard vacuum leak. Check brake booster, PCV lines, EGR if you have it, intake manifold gaskets, throttle body gasket, evap sensor seal



In the future, it's helpful to go through a diagnostic tree to solve your problem. You can save a lot of money on parts in addition to the time it takes to install everything

 

[BIGDDADDI]

All that I changed needed it anyways. I will be changing MAF also. My hearing is bad so I can't hear the leak but my Pops says he can hear it. Now just to pinpoint it out.

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[SnowDrifter]

Can you hear the relative RPM of the engine?

Grab some ether and spray it on the seams in the vacuum system. If there's a leak, your revs will spike

Throttle body gasket

brake booster

Brake booster hose

PCV valve on valve cover

PCV hose from intake to other valve cover

PCV connection at the intake manifold

Intake manifold gaskets. Don't forget to check the other side in the valley, under the manifold

All associated EGR gaskets, valves

Evap solenoid (on top of your intake towards the front)

 

[BIGDDADDI]

Yes [emoji106] I can hear that . I will do this as soon [emoji776] as I get a chance.

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