Howdy folks.. let me get right to the issue.

As the title says this truck is a 1988, it has 113K original miles on it.

Automatic trans.

I got a smokin deal on it but it had some issues all of which I have resolved.. except for this one.

i replaced a leaking O ring on the number one injector last week. it no longer drips fuel. All seems fine except for this.

Afterward it started to not want o idle and acted as if there were a vacuum leak.

I thought it might be TPS related so I ohmed the old one.. it was out of spec so I replaced with a new denso part that I tested before installation. it is also adjusted properly.

Timing is correct.. temp sensor is working, coolant is topped off.

The truck runs and drives fine, good power, acceleration, proper shifting.

i cannot duplicate this issue when I drive it. This ONLY happens in park when it is idling.

Just off Idle1500-2000 rpm it acts as though it is being starved for fuel.. it then starts a cycle of revving up and dropping off.. if I move the throttle valve in very small increments towards the open position the pulse will get faster... until it picks up and revs normally.

if i open the throttle quickly.. it acts correctly.. open it quick to that point and it starts.

Note: once again this is only in park.. I cannot replicate this during driving i have tried.

I am going to attach a photobucket link with a video of its antics.

hopefully someone here can give me an idea of what is causing this.

You can click on the image to see the video.

Thanks.

 

Im not much help, But dam thats a clean engine bay!

Any cracks or leak in the intake tube?

 

must of took that pic in 1988 at the dealer.

 

nope.. it is in pristine condition

 

promise it was just a few days ago.

if you click the picture it links to a video of the issue.