1999 3.4 is hesitating/accerating rough

[ugadawgs]

I have a 1999 Limited with 200,000 miles on it. I have never had any major problems, but the other day it cranked up fine and when i pressed the gas it felt like it was choking itself out. It was very slow to rev up and had the occasionally slight backfire. I noticed recently while accelerating after about 35mph it had a hesitation I just changed out the plugs, pcv valve, and cleaned the MAS and that didnt help. I am thinking it could be a bad ignition coil?

 

[CharliePR74]

Very similar to what happened to my Runner but started with misfiring, then P300 and P306 codes which were related to excess fuel on right bank and finally for my luck, the head gasket of the same bank failed and it started smoking a lot (white smoke). Mine had 199,500 miles when the nightmare started, did the job myself and now has 200,500 on the odometer. Story is, all of them head gaskets start to fail close to the 200,000 miles mark.

I suggest you to check your spark plugs, do a visual inspection on all of them (compare) and also take a flashlight and check the pistons heads. A clean head means coolant intrusion; check also coolant level, sometimes it starts to go down but people think is just normal.

I had also problems with an open injector, that one was causing part of the problem as well and finally do a compression test. Mine was backfiring as well...

 

[sgtstinky]

I just replaced my throttle position sensor due to hesitation during acceleration at low speeds. Not sure about back firing or difficulty starting up, I didn't see that. I also had some check engine codes thrown, can't remember off the top what they were. It was like $55 to replace, easy to install. If you are at 200K you may want to try this since you may need a new one sooner or later.

 

[beerstash]

I have something similar going on, happens when I'm going up a hill at times it feels like its put put putting up the hill but if I accelerate through it stops. I'm also at 195K miles and not sure what all I need to do because everything else has been working great- belts have been replaced 15-20K miles ago, water pump replaced same time... Replace the spark plugs and wires? Fluids on the diffs, trans, and tranny?