1990 Civic Hatch, Base Model converted to MPFI roughly 3 years ago. Things were running pretty well till about 3 weeks ago.
Issues:
1) 3 weeks ago idle started surging and hesitating. Gave me a CEL 14, so I pulled out the EACV and cleaned it with CARB cleaner, which did nothing. I also sprayed CARB cleaner around the vacuum lines and nothing happened. I got a newer EACV I had laying around, purchased 2 years ago, and installed it. Worked fine.
2) last week the weather got really hot. Driving to work was fine, idle was at roughly 800 rpms, but in the afternoon the car seemed to idle low, around 550 rpms. After dinner one night, car started stumbling and hesitating when I took off from stops continued stumbling when I got between 2,500 rpms to 3,000 rpms. Also, CEL 14 came up again. Idle was fine at each stop I had to make, no surging or stalling. Made it home and put in a new OEM gasket from Honda since I used an aftermarket gasket previously. Cleared the CEL code by taking out the ECU fuse and disconnecting the negative battery cable. Reinstalled both after 5 minutes. Ran well for a couple of days.
3) Yesterday, while driving home in the hot weather, I first noticed something was wrong when I was at a stop and idle was very low, like 200 rpms. I thought it was related to my AC being on, so I turned it off and idle went to 600 rpms. Then after 5 minutes of continuous driving CEL light turned on and the sputtering, bucking, and hesitation started again. At stops, no idle surging or hesitation and idle was at a constant 600. I finally pulled over, saw CEL 14, and tried to reset my ECU and waited for 10 minutes for car to cool down. Car started up fine, but a minute into driving the CEL turned on again and all the symptoms came back. Was able to drive the 10 miles home and let the car sit for awhile to see if the idle would surge. It was not surging and was fine.

I was planning on purchasing a new EACV, but in doing more research, read that the EACV has nothing to do with sputtering and hesitation. People on similar threads have said that these conditions were caused by either the dizzy, TPS, vacuum leak, or spark plugs and wires. The dizzy I have, Richporter, is roughly 1 year old, the plug wires are fairly new NGK's, and the spark plugs, I do not remember how old they are. I checked the vacuum lines before and they seemed fine. I even cleaned my FITV and it seems to be doing it's job. I was planning on warming up the car when I got home after work and pulling out the EACV connector to see if it made a difference, but should I be checking anything else, or would a new EACV settle all my problems?

 

Looks like it is my EACV. I drove the car around to warm it up and the idle was around 550. After I parked I unplugged the EACV from the harness and the idle did not change at all. Looks like I'll be changing it out tomorrow.