First off I'm a Toyota guy I bought my first Toyota at 16 it's a 00 Tacoma 4x4 2.7 I bought it with 50k miles now it has 305k and still my daily driver /work truck. Never had any major problems. Since I have collected 5 more early 80s Toyotas solid axle trucks and one has a 2l diesel in it. O have worked on all of these and learned the 22 and 20r well. I just bought a 4x4 98 Tacoma 2.7 ( got it for a steal) it has 200k miles and I've tried all I know to do. It hesitates when you step on the throttle and backfire through the intake. Here's what I've done. Installed new injectors, a completely different throttle body that had sensors in it. I've pulled the MAF, coil packs, plug wires,EGR, and even the computer off my other tacoma and swapped all these parts on both trucks. My 2000 tacoma still runs fine and the 98 continues to idle a little rough and hesitate when I press the throttle down and backfire through the intake. And I cleaned what ground wires I could find on the trick. No fix yet. The throttle body that was on it was really bad dirty. But now it has a different one on it. And I dont get any blue smoke through the exhaust pipe. Some steam and condensation though. Any help would be greatly appreciated. I don't know what else to do with it I'm not getting and check engine light.

 

Did this happen during the purchase test drive?

Couple of wag's here (wild ass guesses) :
- cam timing off
- low fuel pressure

 

No the guy I got it from told me it was having issues and he didn't know how to fix it and didn't want to pay a mechanic to fix it so I asked what he want for it and he told me $350... I bout fell over and went and got it as soon as I got off the phone with the guy. $350 for a 4x4 tacoma with no rust and body in good shape I thought for that I'll get it for a parts truck but hate to do that when it runs. So just trying to get it fixed and it's starting to drive me nuts. I'm used to working on the carb trucks so the sensors and electronics are a little harder to figure out

 

Curious on how you cleaned the MAF...when I cleaned mine with just the spray and still had issues (and the p0171 code), I ended up getting a pick tool on the tiny ass wires and managed to pull off some debris and right after that it ran well without similar issues.

Fuel filter been changed yet? Aif/fuel and/or oxygen sensors too, particularly the one before the converter? PCV valve?

What did you mean by 'backfire through the intake?'

Nevermind cleaning the MAF. Seems like it worked fine on your 2000. Vacuum leak on the 98 perhaps? That's another possibility.

Cheers

 

I did change the fuel filter forgot to list that I have looked for vacuum leaks and have not found any and I checked the pcv valve it's fine. Have not checked the oxygen sensor. The backfire happens when I stomp on the throttle it will stumble/hesitate and them pop through the air filter. When I ease into the gas it won't pop

 

my 3.4 would act weird and backfire if i were to get oil from the k&N filter on the maf. being that you swapped that and there is no change, my next bet would be vacuum leaks, and if nothing there i would definitely do a compression test to see if all the cylinders are good.