Radio Condenser
I've been fighting a similar problem for weeks with my 87 Accord LX (automatic/carb). The problem I'm experiencing is a 'stumble' at a steady speed, no matter if it's 35mph, or 70mph, the sensation is a momentary instant cut out, almost as if the brakes were being applied, returning to normal accelleration, stumbles, etc. This only happens after the car has warmed up, and is most noticable in warm/hot weather. Until it warms up to normal operating temp, it's a smooth as silk. When idling in neutral, the rpm will surge about 70-100 rpm, then drop back, repeating this surge every 5 seconds in a definate timed pattern
Before getting smart, and looking for answers online, I did a quick check of the distributor (cap dry, no cracks, rotor ok), followed by vacuum tube/sensor hell...anyone who owns a similar model will understand. Finally, after several weeks of trying to isolate what I thought was a vacuum leak, I returned to my first thoughts of an electrical issue. In the last two days, I found a discrepancy in the air gap between the reluctor and stator, which after reajusting made a significant improvement, but still had traces of the stumble.
What hasn't been discussed here regarding this problem is the Radio Condenser. I've read several articles reagrding the low of performance, along with 'stumbling', being a symptom of a bad condenser. WA LA! Me thinks, could this, at last be the fix? Hope spring eternal doesn't it?
Well, sorry to report, it didn't. But, it may help someone else here that's experiencing the same issues. So tomorrow morning I'm pulling the distributor once more to check if the air gap has slipped adjustment (did once so far), and check continuity on the condencer leads, and thanks to you all, will be checking the ground strap for corrosion....every so often, very intermittently, I'll see a flash of the BATTERY idiot light. In any event, I'll report back when I find the problem that's been driving me out of my mind...this car is my baby, after almost 20 years, and 235,000 miles it still, or did run like new, same engine, oil changes every 3K like clockwork.