Jorge, Have truck scanned for trouble codes, some auto parts places offer code reading for free and may be a big help in diagnosing issue. It does sound like it could be a large vacuum leak. Check all vacuum hoses for cracks/loose/off. Use a can of starter fluid to spray around vacuum lines, intake manifold base gasket, throttle body, brake booster, etc. While spraying these areas listen for a change in engines rpm, it will change if there is a leak. Good luck.

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