While driving at a constant speed my car bucks or stutters a little bit. I can't really tell if it's bucking (torquing up) or stuttering (torquing down). Probably alternating equally from the norm. Its "mild" but has gotten slightly worse over the last few days.

No problem/detection driving at very low speeds or accelerating. Idle sounds great, drifting with the clutch down is great. Changing the throttle up or down, even slightly, when the car starts acting like it has Parkinson's disease makes the symptoms go away. No, I don't have Parkinson's, myself. The car symptoms started out mild enough to suspect my recovery from food poisoning, but I've been feeling better and the car's feeling worse.

Shuddering problem started after a "snow day" and several idle sub-zero days in an underground (but open) garage.

95 del sol, had the IAC cleaned 4 or 5 months ago to try to fix spontaneous spirited revving while at idle (and I suspect the mechanic changing timings or something to complement the less-than-stellar/efficacious cleaning) that wasn't fully resolved. Problem got progressively better after switching to premium gas (has "detergents"), problem nearly non-existant now (only occurs before warming up).

5-speed manual transmission, the stick is pretty loose normally and sometimes hard to get into R. Yeah, it's probably on its way to gone, but it feels like it might be even a bit more loose now (although R isn't any worse).

Could the clutch/tranny be causing this particular shuddering problem? I had a lot of snow/ice scrape the bottom of the car (the del sol is really low but lightweight so it "swam" over a lot of snow and ice) - could that have loosened/damaged the transmission/clutch?

I was originally worried about the timing belt but it looks good visually but there might be a little slack. Listening to it, there's a slight and small rhytmic "pud" sound. No ping noises ever, no loss of acceleration. Warmed up idle sounds good.

Any ideas? Am I safe to drive this?

 

Have you tried checking the codes? Always a good place to start. If the codes say there is something wrong with a component, it may be the part that is bad or a wiring issue. With a '95, it can very easily be a wiring issue showing up as a component being bad.
Good luck,
Gator

 

Make sure the throttle position censor Is plugged in all the way. My 91 civic did this for about a week before I realized the sensor was slightly unplugged. Under acceleration or deceleration it was fine but trying to maintain speed was terrible.

 

That's great. I had a real bad bucking problem too. It mostly went away when I rewired the harness plug so the IACV would go through the adapter and into the ECU. Its still there a little bit, but not nearly as bad. I had been thinking the TPS may be part of the problem, but wondered why it wouldn't throw a code for that. Some sensors won't throw a code if they are sending a signal, even if the signal is wrong. Maybe that's what is going on. So glad I read this thread again.
Gator

 

have you checked for a vacuum leak?