Having a weird issue with RPM (feels like stick throttle)

While driving to work on these cold mornings my truck has been doing this weird thing where it feels like my throttle is sticking. Here is an example. Getting on a stretch off road, steady on the throttle, 5th gear, doing 50 - 55 mph. Ill come up to a light, from 5th ill push the clutch in, put it in neutral to drift up to the light. Sometimes my rpms will stay up as if i still had my foot on the gas. If i bump the throttle a few times it will then go down rapidly to its normal idle. If i don't bump the throttle it will stay up, then slowly go down a few hundred rpms, then drop rapidly to normal rpm. Its like the throttle is sticking open somehow. It only does this when the truck is in motion, intermittently and is at random times. If i am at a stop and rev the engine to a steady rpm it wont stick. Iv checked the actual cable and throttle plate and when i move it with my hand, it all moves smooth. Iv thought about the IAC Valve malfunctioning or that plunger on the side of the throttle body that prevents the throttle plate from slamming closed. Im kinda confused on this one. When this issue happens, ill press on the throttle to see if there is any slack in the cable that would indicate the throttle plate sticking open, but there isent, there is no slack whatsoever. Would a faulty IAC Valve create a simulated sticking throttle symptom?

 

I am having a similar issue with my 01 Tacoma. If someone could answer this that would be awesome lol recently cleaned my throttle body too so not sure what the issue is.

 

I have the same issue. coming off the freeway I would ride neutral up the ramp to the stop. the whole time my engine would be idling at about 1200 or so. then when I stopped it dropped.

1 thing that attributes to this is the dashpot.

the black capped thing with the white mark on it. i dont know what its really for, but it's a dampener. when you let go of the gas/throttle, it hits this dashpot, and the dashpot slowly brings the throttle arms to a rest at idle.

aside from this. I think this is completely normal behavior for our trucks.

 

i think the dashpot is only on manual transmission trucks. that way when you change to the next gear and let the clutch out, the motor is more in sync with the revolutions of the clutch than it would be if it was at idle.

 

No yah i know about that stuff but for me it stays way up and sometimes revs even higher when i put the clutch in. Like i shift at bout 2500-2800 depending on what im doin and itll stay up there or go higher while i cruze. For a while. And then itll suddenly drop when i get really slowed down. My idle is high too. 1100-2100. Idk about the OP though

 

It closes the throttle plate slowly so that the engine won't run super rich for that split second. It's to reduce emissions.


OP does your truck maintain the same RPM as when you were in gear and you pushed the clutch in?

 

It does not hurt to lube the throttle linkage once in a while .

Then it might be a build up of dirt on the linkage causing it to hang up

Another place to check is where the cable comes through the firewall.

 

My stuttering/balking/hogging issues were solved by replacing the spark plugs which had over 100K on them. It was mostly prevalent when going up a grade at the 3/4 gear shift around 3000 RPM.

 

I actually had this issue before. I got a different cruise control but the pin that holds the cruise control wire on the throttle body was holding the throttle body, I had to give my truck some more throttle for it to stop. Basically had the same issue as OP. Might want to check that out.
Here's some pictures might be hard to see my cruise control computer but its there.

 

A faulty IAC valve would definitely cause this problem. If you replace it, clean out the throttle body while you're at it. You also might want to check for any cracked vacuum lines that may be letting extra air into the motor.

 

Exactly!!! Couldn't have said it better myself! Its as if i still have my foot on the accelerator. And sometimes when it finally does start to reduce, it will stay at 1000rpm and stay there for about 10 seconds then go to the normal 750rpm. Like CodeSeven said other then that my truck runs great. No check engine light and no misfiring or rough idling.

I thought about the dashpod sticking. Ill try and put a little WD-40 on the shaft of the pod and see if that makes a difference. If it does ill replace it.

Im glad to see im not the only one with this odd problem. Just need to figure out how to correct it. This weekend with the snow coming i plan on pulling the intake tube off and having a glance down the throttle body, butterfly and other possible related parts.

Also one other thing that may be pointing to the IAC as the culprit... Iv noticed a few months ago that when my truck comes down from power idle (right after turning the steering wheel, or after coming to a stop) it will actually go lower then 750RPM then increase a little and stabilize and go to normal idle