Surging engine

[maxthrottle]

After having a new serpentine belt put on, the engine has begun surging about 200 rpm up about once every two seconds, at all engine speeds above idle. Currently have 140K miles. Checked the idle air valve, TPS, and MAF. Seemed normal. Don't appear to be any vacuum leaks. Replaced the fuel filter. Ran the codes. Got a 341. Found and checked the SPOUT. Found the SPOUT behind the grill on the left side. Also noticed another unplugged SPOUT like connector near the PCM.
Any suggestions? ANyone know if the unplugged SPOUT is related to the code 341? Thanks.

 

[Royawest]

I don't know what year truck you have ,mine is a 94,but I do know what the spouts are for ,one is for the fuel air mix and the other is to set the engine back to base timing. Do you have air conditioning in your vehicle? Does it work? If not disconect the plug that supplies power to the compresser.That could be your problem. Also your Iac could be going bad but usually that just holds a high idle. I have had the same problem and I have done the air conditioner thing. That worked right quick.