I took my 97 T/A to a repair shop because the engine heated up when stopped at lights, signs, heavy traffic, etc. I thought it was the thermostat, but was told it was a blown head gasket. Had the heads ground, Felpro gasket, valve job, new Optispark, new high performance wires (MSD), new plugs. WhenI got it back it seemed to have lots of power, but idles very rough, especially in gear with the brake on. Didn't do that before. The mechanic told me a couple of things I wondered about. He said the guy helping him put it back together tightened the lifters down too much and bent all the pushrods, so they put a new set in. Then, I noticed that the little hose that fits into the front air intake elbow wasn't plugged in and the hose was just laying in there disconnected. He said "Oh, I've got the plastic piece that fits on there," and went to get it from a shelf or somewhere. Got that plugged in but no improvement in the very rough idle. They said to give it a week for the valves to settle in. I did. Brought it back. They double checked the valve adjustments and found no problem. That has been a couple of weeks ago. Still running the same. Throws a P300 code, but everything seems to check out. I also think I am smelling coolant, but no leak. Is it possible that this yahoo doesn't have some vacuum lines reconnected properly? I noticed that there are 3 hoses coming into the engine compartment on the driver's side and going into a protective sheath. One is fuel supply, one is return and these come out toward the back of the driver's side of the engine. But the 3rd just ends inside the sheath about midway back beside the engine. Just ends. No clamp marks, etc. What is this third line and what should it be connected to? Access to it is gained through a slit in the sheath.
Anybody out there have info to help? I hate to send the car back to these guys. They told me it was a bad crank sensor, but I have no problems with starting and it isn't throwing a crank sensor code. Help, somebody who really knows what's going on. I'm tired of runarounds.

 

Try asking your question on http://www.ls1lt1.com.
There are many very knowledgeable folks there who can help you sort this thing out.