Have a 95 EX 4Cyl VTEC automatic. It has a stumble while cruising at a constant speed. Have done full tune up, cleaned EGR system to include intake runner ports. Put new seals on injectors while I had them out. No check engine light. Any ideas?

 

Exhaust leak before the upstream could cause the problem.
Fuel pump failure
Fuel pressure

Start with basics.

Take a lit cigarette or stick of incense (something with just smoke) and move it around the intake manifold, downpipe and o2 sensor while the engine is running to check for exhaust leaks. Careful not to burn your car up.

If you have access to a scan tool look up to see if all the readiness codes have been completed. If not you may have a pending CEL and soon a light popping up.

If they are completed I would look at the fuel system. You can do a fuel pressure test and then a voltage test at the fuel pump.

You can use the scan tool to monitor the upstream o2 sensor when cruising too. It should fluctuate. My car has had o2 sensor problems without even having a CEL. Replaced it and the problem went away.

What could be happening is that when the car switches back and forth from open to closed loop during certain parts of cruising it is misfiring due to a bad sensor.

I'm throwing ideas out there, not much of an organized approach but see what you can do.

 

Does this happen all the time - even when the engine is still cold or only once it is to normal op temp?

When was the O2 last changed?