Random misfire/bogging

[LA_phantom_240]

My KA s14 just started a new thing today (our one year anniversary) while I was driving on the interstate. Typically, the car is driven in city traffic only, with only a couple trips on the highway a week, usually less than an hour long. Today I needed to go to Alabama to drop parts off for work, and was about two and a half hours one way. Well, about an hour and a half into the trip, I'm going about 75 and I get a random bog/bucking less than a second long... like maybe one or two cylinders misfiring. Didn't think much of it, dropped off the parts, and started to head back. About 15 minutes later, I get the same half-second bog. From then on I got it once maybe every 30 minutes or so. One of the little spazzes lasted almost a full second and had me kinda worried. She made it home, and coming off a light, I went through first, and at about 3500rpm (just before I shifted), it bogged out for almost a second. When I got home, I popped the hood and listened to her idle, listened to the exhaust, looked for anything obviously loose, but I came up with nothing. I have an existing CEL regarding my lack of EGR valve, so I don't know if any new codes are up yet until I pull them tonight or tomorrow.

Here's the car's history.
Bought the car a year ago today, and had a stock KA which had supposedly 90k on it from another s14, had 138k on the body. About 6 months later, I had a problem with my fan controller during the winter that caused it to heat up BAD. Car didn't have any of the typical systems of head/headgasket damage, so I didn't pay it much mind. Until that the clock hit 158k miles, I noticed it was a little sluggish, and noticed bubbles in my coolant, and found another motor. Did a tuneup, cause it was due, and decided to replace the fuel filter as well. Turns out the fuel filter was the ORIGINAL filter, complete with OEM numbers still on it, and the hose would NOT come off, and it was stopped up as HELL. Replaced it with new hose (fuel injection hose), and a Z32 filter. At 163k, I pulled the motor and put in an s13 KA from a wrecked 91 with 80someodd thousand miles on the clock. Used my intake, distributor, etc. Car has a K&N drop in filter, altima fans, ASP crank pulley, DC header, XSPower exhaust (I know, I know... it was free though), and that's about it under the hood. Basics. New cap, wires, rotor, plugs, when I swapped the motor, and its sitting at 165k miles.

I'm thinking maybe the coil in the distributor is starting to get weak when its hot, or something else stupid like that and spark related.