* Fuel Delivery Problems: This is the most likely culprit. A sluggish start suggests the engine isn't getting enough fuel initially. Consider these:
* Fuel Pump: A weak fuel pump can struggle to provide sufficient pressure, especially when cold. The pump might be getting worn out or the fuel filter might be clogged. The engine improves after running because the fuel system warms up slightly, helping the pump's performance.
* Fuel Filter: A clogged fuel filter restricts fuel flow. Replacing this is cheap and easy and should be done regularly anyway.
* Fuel Injectors: Clogged or failing fuel injectors can deliver an inconsistent fuel spray. This is more likely to cause rough running even when warm, but can contribute to a slow start.
* EGR Valve (Exhaust Gas Recirculation): A stuck-open EGR valve can lead to a lean fuel mixture and rough running, especially at cold start.
* Ignition System Issues: While less likely to cause a *slow* start specifically, problems here can cause poor running:
* Distributor Cap and Rotor: Wear and tear on these parts can cause misfires and poor performance.
* Spark Plugs and Wires: Worn or fouled spark plugs and cracked or frayed wires prevent a good spark, affecting combustion.
* Ignition Coil: A weak ignition coil can produce weak sparks.
* Throttle Body Issues (Less Likely): A dirty throttle body can affect idle and throttle response, but it's less likely to cause a dramatic slow start that then improves. Cleaning it is relatively simple and inexpensive, so it's worth doing if the other issues are ruled out. A truly *bad* throttle body usually causes consistent problems, not just a temporary issue.
* Vacuum Leaks: A vacuum leak can disrupt the air/fuel mixture, affecting performance and especially starting.
Troubleshooting Steps:
1. Check the basics: Start with the easiest and cheapest fixes:
* Replace the fuel filter: This is a low-cost, high-impact repair.
* Check the fuel pressure: A fuel pressure gauge is needed for this, often available at auto parts stores. This will diagnose a weak fuel pump directly.
* Inspect the spark plugs and wires: Look for cracks, fouling, or corrosion.
* Clean the throttle body: Use a throttle body cleaner to thoroughly clean the throttle plate and passages.
2. Check for vacuum leaks: Listen carefully around the intake manifold and vacuum lines for hissing sounds indicating leaks.
3. Inspect the ignition system: Have the distributor cap, rotor, and ignition coil checked.
4. Consider professional help: If you're not comfortable performing these checks yourself, take it to a mechanic. They can diagnose the problem more accurately and efficiently.
Don't jump to conclusions and replace the throttle body until you've ruled out these other more probable causes. The gradual improvement suggests a component affected by temperature, pointing towards fuel delivery issues as the likely culprit.
