Hi guys,

I've got a '99 RAM 1500 with the 5.9 V8, 62K and the truck recently developed what can best be described as a slight stumble at idle. It runs fine at speed (I just used it Saturday to pull a trailer with three quads to and from the desert) but around town it has recently developed a slight stumble at idle. Over the past two weeks I changed the plugs, wires, cap and rotor using Mopar parts, I also had the water pump changed due to a nagging coolant leak.

After reading the board and hearing about others who have had this problem (I'm a frequent lurker but don't post very often) I changed the IAC with a Napa replacement, the original IAC was quite crudded-up with carbon. I set the plunger to the same depth as the original was and installed. Re-installed the factory air box (I hate that thing, as soon as I get the truck running right I'm getting rid of it) started it up, I still have the same slight stumble at idle and now I have a whistle which seems to be coming from the intake [:'(] I checked to make sure the IAC I installed is tight (it is) and that the O-ring is in-place (it was) and that the goofy intake is on tight (it was).

So I'm a bit lost, other than the slight stumble at idle (and now the slight whistle) the truck seems to run okay, but what do I need to do to get rid of this goofy stumble?

Any help would be appreciated

--Kevin
'99 RAM 1500 Mostly stock.

 

did you do all the plugs and wire stuff after you had the stumble or before?

 

The stumble started after I changed the plugs, the cap & rotor. I changed the plug wires hoping that would fix it, but it didn't. The whistle just started today after I changed the IAC.

--Kevin
'99 RAM 1500

 

Sounds like something is dirty. Also, there may be a loose connection at the plugs or the distributor.

 

I'm not sure what I could have knocked-loose when I installed the spark plugs, cap and rotor...I did take a mirror and look around the rear of the intake manifold (in the area of the distributor and IAC) and didn't see anything loose or missing, but I'll look again.

Could be, I noticed today that the TB looked pretty dirty, I didn't remove it from the engine but I did spray some carb. cleaner in there while I had the IAC off.

Thanks for the replies!

--Kevin

 

By loose I mean the distributor cap may not be mounted tight; you could have a plug wire that is not securely mounted to the cap or a plug(s); or, you could have a broken plug. Check all connections.

 

I'll check it out, but if it was a loose plug wire wouldn't it miss at speed as well?

--Kevin

 

I had basically the same problem, rough idle, and a big sucking coming from the back of the throttle body & poor mgp. I replaced the iac - same thing, ended up checking the sensors and the MAP sensor was giving funny voltages. replaced that allong w/ the 02 sensor in front of the cat. Drove it a couple of miles and it cleared right up, more power, better idle and no sucking from throttle body, will wait to see about the mpg.


Jackson

 

I had been wondering about the MAP sensor, but all I hear people talking about are the IAC and TPS, but at this point I'm thinking replacing all three since I've already replaced the IAC, have a brand-new TPS waiting to be installed and the MAP is right there. Just wish I knew why it started whistling. One question, is there supposed to be a paper gasket which goes between the throttle body and the IAC? I don't remember seeing one on the old one and the new one didn't come with one.

--Kevin

 

No paper gasket but there should be a rubber o-ring. My new one didn't come with one and but I re-used the old one.