Hi first off I want to tell you that I love the content you put out, your videos are extremely helpful. Here is my question, I have a 92 Nissan d21 hardbody truck that needed new valve cover gaskets so I replaced them, put everything back together but now it has a very erratic idle (surging up and down) I did what you said in one of your videos cleaned the throttle body, took off the mass airflow sensor and cleaned that but nothing has changed. Now when I was replacing my valve cover gaskets I had to remove the intake manifold to get to the drivers side valve cover (also again watched a video of yours showing how to do that, thanks) anyway the truck never did this before but now it just surges up and down at idle. I have checked all of the vaccum hoses for leaks and don't see anything wrong, also cleaned the spark plugs and inspected the plug wires. I have tried advancing and retarding the distributor timing but it still does the same thing just at a higher rpm or lower rpm. it's not my truck it's my wife's and I would like to know that it's safe for her to drive. also it's hard to start now (didn't use to be) and there is a strong fuel smell. It's a six cylinder 3.0 engine with a manual transmission, hope that gives you enough information about it. also I did run some seafoam both in the oil and in the gas tank, Thanks in advance.