Failure at Honda Accord urges help

Good day friends, I have a problem with my 1991 Honda Accord EX, 4-cylinder, 16-valve. The problem is as follows: when I start the car, the engine is very unstable, it wants to stall, and when I accelerate (in park) it doesn't rev past 3500 RPM, as the RPMs start to fluctuate and don't maintain acceleration. I already replaced the distributor and all the wires were checked and they are fine, and the computer doesn't detect any damaged sensors since the check engine light isn't on. It's been in the shop for 3 months and they still haven't found the problem. I urgently need help...

Hello, since it's been in the shop for a long time, I have a question: Have they replaced any sensors, and if so, what did they do? How did the problem start? Regarding the acceleration, does the problem occur at cruising speed?

The car was running fine, then suddenly it wouldn't start. I started wiggling the distributor and it would start, but then it would shut off again. I got another distributor and it started again, but when I turned the distributor it wasn't controlling the timing, and when I accelerated the engine the RPMs wouldn't go above 3500 because they started fluctuating. Also, the engine is very unstable, the spark plugs turn black quickly. They changed the temperature sensors and it's still the same. The check engine light is off and it's not showing any codes

First, I would check the ignition timing at all points. Check the sensor harnesses to make sure they aren't broken or loose, and check the engine and computer ground connections

Also, check the vacuum lines; sometimes in these faults, going for the simplest solution works