I've changed coils, spark plugs, wires, transmission oil and pan, etc. General tune-up stuff.

I've tried Shudderstop stuff- just in case - no difference

I needed to change out the AC fuses yesterday and said, what the heck, let me change out the fuse for the fuel pump while I have this open. THAT change seemed to help a bit. NOW rather than getting multiple hiccups --little ones but all in a row at times) betweeen 35 and 65 (mostly the speeds I drive). I am getting some single hiccups.

The fuel filter is due a change out, so that's in queue for later this week. From reading the forums, it sound the like order of throwing money is troubleshoot and fix this issue is:

Change the fuel filter
Clean out the engine - What cleaner do you recommend for a 97?
Check for vacuum leaks
Check the fuel pump
Check the transmission

The hiccup does NOT seem related to shifting gears, but it makes me wonder.

Advice for the order of money loss, I mean maintenance, that helps me diagnose and resolve this issue welcomed.

I love to drive long distances and I'm feeling like I should remain "grounded" until I resolve this issue. ''

 

One of the most important, the fuel filter, should be changed first. Just a reminder, pull the fuel pump fuse and allow the engine to run out of gas (eliminates fuel pressure in fuel lines), then you can remove the filter without getting too big a fuel bath. After you remove the filter empty it out into a clean container in the direction the fuel went in so you can see just what is/was in there. Check the wires at the crank sensor for looseness or rubbing on anything , touch all the bases.

As far as cleaning engine, outside maybe, inside regular oil changes should handle that.