When I start my truck warm or cold, it idles for a couple seconds but then starts idling high up to 2000 to 2500 rpm. The check engine light blinks a few times and the rpms drop to almost a stall and then recovers to a normal idle. Sometimes when it drops to almost a stall, it does stall. What is causing this? After all of that the truck runs fine
Check engine light blinking typically means you have a misfire (s).
First thing I would do is get the computer (OB2) scanned. This will make it easier to help in the diagnosis. Most auto part stores will do this for free. When you get the codes, write them down and let me know what they are. There are many problems that could create this symptom and without speculating for hours let's try this out first and I'll be happy to help you out in finding the problem.