Here's one for you engine gurus:

I just put a new set of plugs into my truck at 62K. Truck starts and runs just fine, but when I rev the engine in park sitting in the driveway, she starts to lope and shake at about 3000 RPM. It's not misfiring, she still is hitting on all six. No cold cylinders. No smoke or any other funny noises, and no warning lights. So, just for grins, I take her out for a test drive, and everything is fine. I had her up to 5500 RPM hard acceleration and she didn't miss a beat.

So, my two WAGs are that 1. I hit a rev limiter and the settings are different in park and while driving, or 2. I might have tweaked a plug wire while pulling a boot off.

Can anybody out there shed some light on this for me? I'd appreciate it!

 

I think the 3.0 is limited to reving only to 3000 rpms in park.you are hitting the rev limiter.

 

I have a 91 3.0L. I can redline mine if I wanted to...

 

You hit the rev limiter in park. I have an 01 XLT with a 3.0L and it will limit it to 3K in park also. It does have two rev limiters and they are set at different limits.

 

yep its rev limited