Mystery noise from engine in my Toyota 4 runner

[Traveler]

I have been attempting to get my 1996 4 runner ready for a smog test: cleaned the MAF with CRC MAF cleaner, changed spark plugs, changed oil to 5w-40, new oil filter, new battery, new alternator (old one was not charging battery), located and repaired vacuum leak, ran injector cleaner thru system. It seemed to be running just fine, when all of a sudden it developed an engine noise. Checked oil and it is way too dirty after only a few miles
I'm no mechanic and I can't really describe the noise, but it sure as hell is not normal. The faster I rev the engine, the faster and louder the noise.
Truck starts up just fine, but after it warms up it shudders and stalls.
Next step: I will be adding Motor Medic engine flush and running it for 5 minutes, then changing filter and oil AGAIN to 5 w-30.
Don't know where to go from here. Any thoughts greatly appreciated.

 

[2Gjunkie]

Can I make a suggestion? — if you have an unhealthy motor and you don’t know what’s wrong with it, don’t use an engine flush as part of your diagnostic process.
People have differing opinions about flushes. I use them as basic PM on engines that I know are running decently—at long intervals (like 30,000 or more) to help get rid of varnish and things like that. Especially if the engines run on the hotter side or if I have a high-NOACK oil.
In your case, I think you’re more likely to end up with some gunk that gets worked loose and ends up clogging a lifter or sludging your pickup tube.
Whatever your problem is, engine flush is probably not going to make it better, but is likely to make it worse.

 

[Traveler]

Since I know so little about auto mechanics, I have been grasping at straws.
It is so strange how the noise problem came about.
I was idling the truck and when it warmed up, it stalled and died. When it cooled down, I restarted it and THAT is precisely when the mystery noise started. I have not driven it since that time.
I'm stuck in Mexico, just a few miles from the border near San Diego, and I don't want to be ripped off by some un-ethical mechanic.
If I can't fix it myself, or at least precisely pin point the problem, I'll be forced to sell it as a parts truck. HUGE loss.

 

[spyderdrifter]

Can you post a video of your noise to help out? +1 on not using the engine flush. It's just a waste of money in my opinion. I used it a lot at my old job (not by choice) and it never did anything positive, and at $100 per flush (what the shop charged for the entire service), it was as I said, a waste.