95 Tacoma 3.4L missing/hesitating

I noticed my 95 Tacoma 3.4L hesitating really bad during acceleration and especially on the highway cruising. It seems to be worse at about 60mph and lightly accelerating or while in cruise control when the engine trys to compensate for a slight upgrade or hill. The truck will start bucking like crazy until I let off just a bit on the gas. It starts and idles fine. Then the next day on the way to work the engine light came on and the code was P303 # cylinder #3 missfire detected.(how the hell the cpu can detect a missfire is beyond me). Anyway so I check the plugs and find a hair-line crack in the ceramic insulator, the others were fine. So I replace all with new 2 prong denso oem plugs. The coil pack rubber tube that connects over top of #3 cylinder's spark plug was a bit more brown than the other two cylinders. So I check the resistance of both the primary and secondary windings of all 3 coil packs and they were all about the same and in spec according to Haynes manual. I then clear the code from the computer and I take a ride and the same bucking/hesitation problem, but I don't get any codes and the engine light does not come back on. So I replace the air filter, fuel filter, plug wires and pcv valve but this didn't help, same problem. I don't know what else to check short of bringing it to the dealer, but they charge an arm and a leg. Does anybody have any ideas to what might be going on, I would greatly appreciate any input, thanks. Sorry for the long post!

Hey.. you might want to check your mass airflow sensor.. sounds similar to a problem I had this past summer on my 99 3.4L... except I had the check engine light come on and I believe it was P0171.. system too lean. Anyways, it idled just fine, but was jumpy, had no power and used twice the normal fuel. Dealer who did the diagnostic told me it was the front O2 sensor.. changed that and $250 later it was still running badly.. then they convieniently said that that MAS was also gone.. I had that. Anyways, $500 later my truck ran. I have since read that you can clean the MAS with electrical contact cleaner.. wish I had know that a year ago! Good luck..

Hey. Read your post.
I also have a 95 Tacoma, but although I haven't had any trouble out of it, I have had the same problems with my Toyota Celica.
The celica started buckling/hesitating real bad and I did the same thing you did. The whole nine yards. Basically a complete tune-up. I astill had the problem.
So I gave in and called a mechanic I semi-trust :) He said it sounded like it may be the throttle position sensor, so I went out and bought one. I put it in and haven't had the problem since.

It was about a $25 fix after all that cash I spent. :)

You may want to look into it. It can definitely cause hesitation/buckling.

Yea , I was thinking the same thing about the TPS being the culprit. I took "Northern Taco's" advise and cleaned the mass air meter with electrical contact cleaner, but this didn't help. I went for another drive and noticed that it will hesitate upon gradual acceleration between 50 and 75mph. If I am going 80mph and gradually accelerate it drives fine. I also disconnected the TPS and did resistance checks with my multi-meter and all readings were in spec. I am wondering if there is a slight bad spot in the TPS at a certain throttle position and every where else is ok? Could this be a speed sensor problem? Remember I am not getting any codes from the cpu, engine light doesn't come on. Thanks

Just want to let everybody know what the problem was just in case someone encounters the same thing. If you read my previous posts my truck was hesitating under load. I finally broke down and took the truck to Priority Toyota dealership on Military Hwy. in Chesapeake, Va. (by the way if anyone lives in the Hampton Roads area of Va. DO NOT and I repeat DO NOT take your toyota to ADVANTAGE First Team Toyota on Portsmouth Blvd in Chesapeake, VA. they suck it is a long story but trust me they suck!) Anyway, If you read my previous posts I measured the resistance of the 3 coil packs and they were in spec acccording to the Haynes manual. Well obviously I couldn't measure them while the engine was running but that is when they would start to break down. The toyota dealership hooked up their SCAN meter and went for a drive, then downloaded the data and found that all 3 coil packs were breaking down while the engine was up to temperature. The coil packs have been replaced and my truck runs like new again. If you live in the Hampton Roads area of VA. and you have to take your toyota to the dealership I highly recommend Priority Toyota on Military Hwy in Chesapeake, VA. and I am no way affiliated with them they just did a good job!I hope this helps someone out there, peace!

onebadmust, I live in Va Beach, and I've been using Charles Barker Toyota (Where I purchased the Taco), but I may give Priority a try, Barker always seems to take longer than I'd expect, thanks for the info.

Good Luck

Oh yea, how much did the coil packs cost to have replaced at the dealer?

Thanks again,