Timing chain is generally used with push rod engines..some even use direct gear drive. Over head cams are way out and driven by belts..and after a while a belt can slip a cog or two...or simply breaks...the 3.4 uses a chain to intermediate sprocket then a belt to the cam sprockets...but the belt is more prone to be the culprit than chain..although chains can also slip a notch or two..or three with a former car...long time ago.
Anyway, at 130,000 miles, replacing the timing belt is "standard maintenance", be it the actual problem or not in your case.
I suggest you go to
www.autozone.com to get complete details for this procedure specific to the z-34. This drawing
www.avigex.ca/z34/timingbelt.gif is from them.
About the "car jumping"...not clear if related to this....may be some backfire due to unburned fuel or poor timing..
But yes, a timing belt that has jumped several cogs can be a non-starter...