I have a 93 with a 4.9 and a standard. Every once in a while it will go through a spell where when I disengage the clutch, the rpms will shoot up about 500 and hold for about 7 or 8 seconds. or when you just let off the gas, it wont engine brake. it just acts like your still on the gas for the same amount of time. It almost acts like its lean to me? but idk where to start. any help is appreciated

 

Hey Wiley, start by checking for vacuum leaks, especially around the throttle body. After that, concentrate on cleaning/testing your Idle Air Control Valve (IAC). Good luck, Peace, Dave.

 

thanks ill give it a shot

 

So the chase of this problem has been rather strange. I used the old starting fluid method and could not find any vacuum leaks. So I replaced the idle air control valve and it seemed to make the problem worse. Out of ideas, I got curious. I unplugged the idle air control valve and drove it. I haven't had one bit of trouble since. If anyone knows of a reason this would be harmful in anyway please let me know but as far as I can see, it shouldn't. Thanks for the replies.

 

If the throttle linkage has a stop screw on it, it's misadjusted. It should stall when the IAC is disconnected.