Hey guys, I'm new to this forum and I've got a lot of questions. So I recently bought a '90 4runner 3vze auto 4x4 with 140k miles on it to daily drive in the winter. When I got it it seemed to have the running rich and high idle issue along with poor fuel mileage (about10mpg) I've heard about in other threads, however I wasn't that worried about it it seemed to run well enough and have reasonable power. The real issue I need to address is that the other day I was driving it to town and made it about 2 miles from my house and it pretty much died on me. From the time I started it that morning it was odd it hard started and then when it did start shook fairly violently for just a second then smoothed out. so I was a bit apprehensive but continued on my way after about 3 minutes warming up when I first took off it would not shift out of low gear revved up nearly to 5000 rpm then I stopped put it in park, back to drive and it was business as usual after that shifted like a dream. So I get out on the highway and right away it seems way down on power, I have my foot clear to the mat and I'm struggling to make it to 55 miles an hour. Then after about a minute of holding it WOT it completely falls on its face no power whatsoever and I pulled off on a side road put it in park and it died. I did get it to restart and it runs very poorly will not idle on it own, smells extremely rich and will only go about 20 miles an hour with my foot to the floor. I really am at a loss, I haven't found another thread with a problem just like this one and I'm not all that familiar with these Toyota's, though I do have a reasonable amount of mechanical skill and tools to back it up I don't know what direction to head here. If anyone has any ideas or a different thread to refer me to I would greatly appreciate it, I don't really wanna take it to the dealership.

 

This could be a bunch of different things, but the first that comes to my mind is that your timing belt may have jumped a tooth, then jumped another.
When was the last time it was replaced, has it ever been?
start with some basics, check your spark plugs/distributor cap/rotor/plug wires, take the timing covers off and line up the marks on the crank and cams to see if they line up and have a look at the condition of the timing belt.
high idle is usually caused by a vacuum leak, so you may have more than one issue to work on.
whatever you do don't just fire the parts cannon at it, test test test.

 

Yeah I definitely don't want to just start throwing parts at it I've done some testing on it already, no engine codes good fuel pressure good spark put brand new plugs in it today because the ones that were in it looked pretty bad but no change. I am wondering about the timing but I find it hard to believe that it would jump a few notches without some sort of catastrophic event like a backfire or internal engine damage, as far as I know its never been replaces so it wouldn't be a bad idea to just go ahead and do it . I am leaning wither towards timing or a massive vacuum leak somewhere and I don't really know where that would be at, I haven't put a vacuum gauge on it but I did hold my hand over the intake as I cranked it and it seemed to have good vacuum. I also was thinking about doing a compression test but it seems to crank the same as before not like its lost any compression.

 

One way you can find a vacuum leak is to open a propane torch without lighting it and wave it around suspect area like intake gaskets and vacuum hoses, just stay away from the distributor. You can do the same with starting fluid or brake cleaner. check the rubber intake boot between the VAF and the throttle body for splits as well.
It is still a good idea to check all your basics first and the only time I ever use the parts cannon is to eliminate regular maintenance items like cap/rotor plugs, fuel filters and such just to get some known good parts in play to help with diagnostics. You say it's been running rich so I wouldn't suspect fuel filter or pump.
Eliminate all of the basics first, compression, spark (at the correct time) and fuel. If you use the timing mark on the harmonic balancer don't forget that the outer ring is bonded to the inner with rubber and they are known to separate and your timing mark will migrate.