I have a 1997 4runner with the 3.4 and automatic 4wd. It was running great with one cel for a bad cam sensor. I replaced that, crank sensor, air and fuel filters, spark plugs, wires and coils, iac, temp sensor, pcv valve, and Mas sensor and still can't figure out what's wrong. It idles high (1300-1400) at initial start, but doesn't drop when it's warmed up without backfiring. But as soon as I turn on the ac, it backfires and idles very rough. And when I put it in gear, it backfires like crazy and immediately stalls every time. I've checked for shorts, vacuum leaks, and broken wires. Nothing found. Everything seems fine. The tps also seems to be working but I can physically rotate throttle and it doesn't always return exactly to its regular position. It also has 0% fuel trims at idle and 18% throttle position at idle. And air flow rate is about 1.9 lb/min.

 

Did you replace your sensors (crank tps, maf, temp) + iac with toyota or off brand?

I am dealing with high idle on my 98 3.4 manual. My tps shows 10.2-10.6 at idle at about 650rpm. My throttle body will stick anywhere from 11 to 12.4 on occasion with idle up to 2400 rpm. If I rotate the throttle (engine off...) fully open there is a lot of horizontal play in the shaft. I was told there should be about 0.03" of movement and I have 0.06". After ruling out the other causes I decided to buy a new throttle body and hope to get it installed in the next few days.
I never had any backfire issues. when warm can you close the throttle manually and achieve normal idle rpm?

 

some parts I bought an off brand to see if it would change (still good name brand just not oem brand). And when nothing changed at all, i returned the part. And i also feel like there is a lot of play in the throttle body and i watched a video somewhere and the guy had idling provlems and stuck a tiny washer where the throttle cable assembly slides flush with the throttle body and that fixed it. But I don't think it's that. I have also done extensive tests on the tpms and the iac/Mas wete both replaced with used factory parts with zero changes. I was only getting misfires recently from cyl. 1 and 4 only even after changing plugs and swapping coil packs around.. cleared the codes and they came back up for the same cylinders. At this point I am thinking it may be the fuel injectors might be clogged or going out. I've read that a misfire in one cylinder can cause its sister cylinder to misfire since each one is connected by another. 1 and 4 are sisters. I'll try that once I have money to replace injectors and the plenum gaskets once again.