1988 Dodge Ram D100 with a 318 throttle body When you start the truck it sounds fine sometimes idols high then dies It when let off gas and still have g?

A 1988 Dodge Ram D100 with a 318 experiencing high idle, then dying when you let off the gas, and still having a rough idle points to several potential issues, most likely related to the carburetor (assuming it's a carbureted model, even with the mention of a "throttle body" - early fuel injection systems on these trucks were very different from modern throttle body injection). The mention of a throttle body is confusing, as the 318 in an '88 D100 would *not* typically have electronic throttle body fuel injection. Let's cover the possibilities:

If it's a Carburetor:

* Vacuum Leaks: This is the most likely culprit. Small cracks in vacuum hoses, a loose connection at the carburetor, or a leak in the intake manifold can cause erratic idle and stalling. Check *all* vacuum lines for cracks, looseness, and proper connections. Pay close attention to the PCV valve hose and the brake booster line.

* Dirty or Clogged Carburetor: Years of use lead to build-up inside the carburetor, affecting fuel delivery and air/fuel mixture. A thorough cleaning or possibly a rebuild might be necessary.

* Idle Air Control (IAC) Valve (if equipped): Some later-model carbureted vehicles used a basic IAC valve to help control idle speed. If yours has one, it might be dirty or malfunctioning.

* Fuel Delivery Problems: Check the fuel filter (replace if necessary), fuel pump pressure (should be within the specs listed in your owner's manual), and fuel lines for any blockages or leaks.

* Choke Issues: The choke is responsible for enriching the fuel mixture during cold starts. A malfunctioning choke can cause high idle or stalling.

If (Unlikely) it's a Very Early, Primitive Fuel Injection System:

* Throttle Position Sensor (TPS): A faulty TPS can cause erratic idle and stalling, especially when the throttle is released.

* Idle Air Control (IAC) Motor (different from the carb IAC): Similar to the carb version, but on a fuel-injected system, it's responsible for maintaining idle speed.

* Fuel Pressure Regulator: Incorrect fuel pressure could lead to these symptoms.

* Mass Air Flow (MAF) Sensor (less likely for '88): A faulty MAF sensor could lead to incorrect air/fuel mixture calculation.

Troubleshooting Steps:

1. Check for Vacuum Leaks: This should be your first step. Use a vacuum gauge or a spray bottle with carb cleaner (carefully) around suspected leak points. A change in engine speed indicates a leak.

2. Inspect the Fuel System: Check the fuel filter, fuel pump pressure, and fuel lines.

3. Clean or Rebuild the Carburetor (if applicable): If you're not comfortable doing this yourself, take it to a mechanic specializing in carburetor work.

4. Inspect and Test Related Sensors (if fuel injected): TPS, IAC, and MAF sensors (if applicable) should be checked or replaced if faulty. This often requires a multimeter and some knowledge of automotive electrical systems.

Important Note: The "throttle body" mention is confusing in the context of a 1988 Dodge Ram D100 with a 318. Almost certainly, it does *not* have a modern electronic throttle body. Double-check what kind of fuel system your truck uses (carburetor or fuel injection) before pursuing solutions specific to a throttle body. Look under the hood; a carburetor will be much more visually prominent than a fuel injection system. If you are unsure, providing more details (e.g., a photo of the intake manifold) could help clarify.