2000 LX470 Missing Under Load on Cold Start Only

[Mattman615]

I have recently become the owner of a 2000 LX470. It’s the Gold edition, (Air-ride, sunroof, leather, AWD, V8, etc) This girl has had several timing belt replacements, and has been kept up very well. It has had several because the previous owner had it replaced once, and then the tensioner broke after replacement. He then had it changed out again. Any how, I’ve began to notice a lack of power and a straight up misfire on cold start only. This only happens when it is below Normal operating temp, and it is enough of a misfire that I can feel it stuttering, and it has a very strong hesitation to accelerate. It has new plugs, new fuel filter, And new air filter. It also has no stored trouble codes, and does not trigger a check engine light, as well as any other in dash monitors, and has not since this began around 3-4 months ago. Please give me a word of advice!! 
 

[Pwrdud3]

I have the same issue but, my old dawg is a 98 with 375,000 on it. The issue started after the need to replace an ignition coil that was cracked down the length of the shaft. This caused a severe misfire of that particular cylinder. After replacing them all though, I have the same issue. Only at cold start and I've pretty much done the same thing, plugs, fuel filter, air filter....Likewise, no codes, notta. Now, I hooked up a mid-low range diagnostic meter and noticed that fuel back #2 reading was much lower than #1. I suspect that may have something to do with this particular issue that we both are experiencing. I will keep you posted as I am going to figure this one out. It drives me insane to have a misfire, even if its only a cold start issue.

[Pwrdud3]

I’ve found the issue, replace your valve cover gasket’s. If you are having what I call “bubbling” and it seems to be fuel or ignition coil fault, it’s actually a vacuum leak from loose valve covers. I replaced both of mine, sealed her up good and tight and now she purrs like a kitten. I noticed that the bolts to the cover were loose enough I could turn them with my hand. Problem solved 😁