Tranny going?

[Canuck4x4]

...I bought a 2003 xlt 4x4 4.0 with an automatic transmission about a month ago. Engine/tranny has been working great. Tonight after work I got up to 55 mph and I felt a strong jolt/bucking sensation. I thought maybe I had bad gas. Put in some fresh gas and methyl hydrate and it didn't help.
...sometimes if I cruise at 55 mph, and then I accelerate up to 60...it will jolt/buck then go away. Or if I cruise at 60 mph...then slow down to 55...it will jolt. If I pull away from a stop and accelerate up to 60...the shifts are nice and smooth. If I kick it down at 55 or 60 mph...it accelerates hard and " is NOT " slipping at all. Is this a easy adjustment....or is my tranny going??
Thanks

 

[Transman304]

Is your OD light flashing? Sounds like a lock up issue.

 

[Canuck4x4]

Is your OD light flashing? Sounds like a lock up issue.

...No it's not flashing. The transmission has been working awesome until tonight. Could it be something other than the tranny?

 

[Canuck4x4]

Does it sound like a costly repair?

 

[adsm08]

Do a tune up, complete with coil pack and wires. It could be a weak coil causing a misfire. After that the only real option is a crappy torque converter lockup, which is not cheap, but not hard to do yourself either.

 

[Canuck4x4]

...It is a 2003 with 67,000 miles on it, so there is a good chance it has the original plugs, wires ect. I am going to take it to the transmission shop on Friday for a test ride. Thankfully, the owner is really honest and is well respected.

 

[Canuck4x4]

Update-last night I sprayed wd40 on the coil pack and wires. I drove around for about 30 minuits and it was still jolting/bucking. This morning my commute to work is 25 miles and it didn't act up once.I varied the speed between 55-65 mph and it ran flawless. I have had bad plugs, wires, fuel filters, slipping trannies ect, in other vehicles and I have never experienced this bad jolting before. Since it ran good this morning...can I rule out a transmission problem??. I'm going to clean the coil pack ground plate and change the plugs and wires.

 

[Canuck4x4]

....stopped in at the transmission shop last night. Explained what's going on and was told it's not the transmission. As mentioned here, was told the likely culprit is a bad coil pack. Then I realized something..the only time it's acting up is when it's snowing out and the snow is blowing through the grill. Picked up a new coil pack, plugs and wires. Hopefully this is the problem.