I just changed my spark plugs and engine runs nice and smooth as I increase the rpm's to 3000 while in park. However, I am trying to figure out what happens at 1000 rpm as the engine is either resonating or running rough. I find it odd that the engine can smoothly idle at 800 and run smoothly all the way up to 3000 rpm but seems to run rough (maybe resonance) at exactly 1000 rpm.

I would like to hear any thoughts or comments about this.

 

what specifically is running rough? I had a misfire and faulty coil that caused the whole truck to shake (in neutral) between 1000-3000 rpms. Above 3,000 rpms she run smoothly again. At idle it was smooth, too.

What type of exhaust do you have???

 

The exhaust is standard. This only seems to be happening at EXACTLY 1000 rpm which is why I am curious if it is some sort of resonance. 800-900 rpm is fine. 1100 rpm and up is fine. It does not seem to be a mis-fire. I don't usually push the gas pedal down very slowly to listen for problems but I just changed each of my spark plugs one by one and would start the engine after each spark plug change to check the engine. I forgot to plug back in a coil a couple of times so I definitely know what the mis-fire acts like.

I don't notice it during regular driving since I am accelerating with the engine in gear. I guess I could try to run at 1000 rpm with the engine in drive to see what happens.

 

my truck does same thing, 1000 to 1350 rpm, stutters and almost dies, only does it when warm,not cold. it doesnt seem to afeect drivability but is annoying to know it does it. i have dual exhaust with offroad pipe,mil eliminators and hooker headers, but they were on long before this problem began. anyone have any thoughts or solutions.

 

I reset my computer so I guess I better let it learn for a 100 miles. I changed my spark plug gaps and I found the crankcase air hose was not plugged into the elbow which created a vacuum leak. I am getting a slight stutter at 1350 now but I am going to wait out the 100 miles and see if the computer needs to figure out the air/fuel ratios for each RPM increment.

I have heard that the TPS (throttle position sensor) can sometimes get glitches in them that might cause the computer to make incorrect air/fuel ratios. It can be tested by hooking it up to an ohm-meter and then turning the sensor slowly. A glitch would be very low resistance or very high resistance for a short period while turning the TPS.