Surging at cruising speed....

[MATCHBX]

Some of you know we've been having some issues with Terina's car. Here's the skinny,

When driving down the highway at cruising speed (not hard on the throttle and not having the foot off of the gas), the car starts to surge a little. It happens at varying rpm's and throttle position. We thought it might have been a stretched timing belt. We replaced the timing belt and components and it still was acting up. Thinking it was something to do with the tps or something else in the throttlebody, we swapped my thottlebody onto her car. It didn't fix the problem. It doesn't kick and buck but kind of surges real gently (enough that if done too much, it would lull you to sleep). It seems like it happens most around "0" on the boost guage. But if it is sitting in the driveway idling and you rev it up, it seems to miss at the higher rpms.

List of mods,

MBC
Free mods
Boost guage
Removed PCV valve and routed port into intake hose (tee'd into one of the other hoses that go there)
8mm sparkplugs wires

No CEL's are being popped when this happens. It has new plugs and wires. Could it be something with the fpr or the fuel pump? It pulls very hard all the way thru the rpm range. In fact it pulls harder now after we got done doing the timing.

Any ideas of what to look at to diagnosis this? I have a datlogger but haven't hooked it up yet. Let me know what I should be looking at on the logger.

Thanks

EDIT: Sorry. Forgot to mention, this is a 92 AWD auto with 110,000miles on it.

I would start off by checking to make sure I had no vacuum hose leaks.