1993 regal 3800 with 113xxx. problems started about 5 days ago, rough idle, runs very poorly about 5 minutes after driving, car wont downshift, speedo goes crazy, from a dead stop takes 10-15 seconds to clear an intersection. Im pretty sure its the ecm since i just replaced the plugs and wires. Anyone else care to throw an opinion my way? Thanks.

I'm afraid it could be a lot of things.
Fuel pump
ICM
ECM
Poor battery connections
Poor grounds
& others

Have you checked for codes?

There have been no codes pulled and no check engine light. I am going to check the battery terminals and ground and if that doesnt do anything ill probably end up getting a new ecm.

Cables & grounds should be the 1st thing checked - it doesn't cost anything.
If your Regal has 2 battery cables that come together under a single rubber boot then you have to get the boot off to clean the cable ends.

I'd also remove the coils & ICM & check for corrosion between the mounting plate & ICM. Another freebie.

While the coils are off you can check the resistance of the primary & secondary windings. A weak coil won't throw a code.

When was the last time the plugs & wires were changed? I'd check them before getting an ECM.

i got the car back from a good diagnostics shop here and it was the ecm. thanks for the help.