vehicle intermittently misfiring goin up hill under load and sometimes upon starting. replaced plugs and wires and am not getting any mil codes. any ideas would be appreciated.

 

There are a few reasons this could be happening.
1, Crank sensor
2. Ignition module
3. Throttle position sensor.
4. Contaminated fuel
5. Fuel filter
6. Coil breaking down under load
If you haven't changed the fuel filter yet, that would be the first thing I would do.
Just because I listed some possibilities, please don't go changing parts without being reasonably sure. It can get expensive just throwing parts at a problem.

 

changed filter and car still does it , but have gotten 2 mil codes since one was random misfire and the other was #5 cylinder misfire. what is best way to isolate by testing so i'm not just throwing parts at the car?

 

hookeed up fuel pressure tester and found pressure dropping when key off, changed regulator and that cured that problem fuel pressure when key on 22psi with engine running 36. still has very intermittant chugging up some hills and sometimes after killing car and it sitting for 30-40 minutes very hard starting .starts and dies several times until finally it will rev up above 1500 rpm it smooths out then runs fine . checked crank sensor ,tps,cam sensor,map sensor ,coil packs-all tested good.driving me nuts not making sense. any suggestions will be greatly appreciated

 

Have you checked the plugs and wires? Could also be a vacuum leak, or a bad cat

 

It sounds like the engine is breaking down under load. Can I ask how did you test the things you said you tested. You cannot confirm electrical performance of some of those parts by just an ohmmeter test.
After sitting the 30-40 minutes try cycling the ignition switch to allow the fuel pump to fill the fuel lies before trying to start it. Does that make it start any easier?
Things like crank sensors and coils will often check good with an ohmmeter , but will not deliver under load.

 

changed fuel pump and that raised fuel pressure and seems to have stopped hard start problem, but still seems to stumble some on hills

 

I have a '94 LeSabre with the same simtomns. Any other ideas would be of great help. Would Cam Shaft Position Sensor cause this?

 

Check everything in the area of #5 cyl. Could be poor connection at injector, hard to see vacuum leak. A good visual inspection is important. Coil could the culprit.

 

Hanky,
Since you were getting some pressure leak down on the fuel pressure, you might have a leaky injector at cylinder 5.
That would explain the hard starting as well as the miss.

It only takes a few minutes to swap out an injector for a try.