After driving your 1995 buick park ave. for a long time car go over 10 or15 mph If you let it sit try again will fine but then have the same problem Could be coil packs?

It's possible, but unlikely that failing coil packs are the sole cause of your 1995 Buick Park Avenue's problem of losing power above 10-15 mph. Coil packs usually cause misfires that are noticeable across the entire RPM range, not just at higher speeds. While a failing coil pack *could* contribute to the problem, it's more likely a symptom of a larger issue, or part of a group of issues.

Here are some other possibilities that are more likely culprits:

* Throttle Position Sensor (TPS): A faulty TPS won't give the engine the correct information about throttle position, leading to poor performance at higher speeds.

* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate air-fuel mixture information, potentially leading to power loss.

* Fuel Delivery Issues: This could include a clogged fuel filter, weak fuel pump, or problems within the fuel injectors. At higher speeds, the engine demands more fuel, making a fuel delivery problem more noticeable.

* Transmission Problems: If the problem is specifically related to speed and not engine RPM, it might point towards a transmission issue. Low transmission fluid, a slipping transmission, or internal transmission problems could cause power loss at higher speeds.

* Ignition System Issues (Beyond Coil Packs): While coil packs are part of the ignition system, other components like the distributor (if applicable), ignition module, or crankshaft position sensor could also be at fault.

* Vacuum Leaks: A vacuum leak can affect engine performance significantly, especially at higher speeds and under load.

Why it might seem better after sitting:

The temporary improvement after letting the car sit suggests that heat might be a factor. Overheating components (like the MAF sensor) might malfunction when hot but function adequately when cool.

What to do:

1. Check Engine Light (CEL): Has the check engine light illuminated? A code reader (available at most auto parts stores) can read any diagnostic trouble codes (DTCs) stored in the car's computer, providing valuable clues.

2. Inspect obvious things: Check your fluids (transmission fluid, engine oil, coolant). Look for any obvious leaks.

3. Professional Diagnosis: Given the complexity, it's strongly recommended to take your Buick to a qualified mechanic for proper diagnosis. Describing the issue exactly as you have here will help them pinpoint the problem. Throwing parts at it without a proper diagnosis can be costly and ineffective.

Don't jump to conclusions about the coil packs until you have a more thorough examination. The intermittent nature and speed-related aspect strongly suggest other underlying problems.