Ok nobody can ever help me on automotive forums.com so i will post this here in hopes of some ideas.

I dont know what happened with that post, here is what i was trying to say.
I am Still trying to figure out my horrible fuel economy (11.4 mpg)and lack of power i checked fuel pressure and cat both are fine all injectors are clicking. I was leaning towards ignition control module i thought it seemed like a sensor and that's about the only one I haven't replaced. Then i was told I would experience hard starts and stalling I had niether. Then on my way to work last week in the morning I went to start my lac and nothing just dash lights when I turn the key. Then I got under checked wires on starter all are fine and tightened the battery cables. Still nothing I let it sit about ten minutes and it started. Did the same thing day before yesterday too.could this be the Ignition control module? how do I test it ?
__________________And by lack of power i mean i have to floor it to get up to speed on the highway then let off the gas slowly. someone please let me know what you think i need better gas mileage!

1990 Cadillac Sedan Deville 4.5 v8

 

what? try again.

 

I dont know what happened with that post, here is what i was trying to say.
I am Still trying to figure out my horrible fuel economy (11.4 mpg)and lack of power i checked fuel pressure and cat both are fine all injectors are clicking. I was leaning towards ignition control module i thought it seemed like a sensor and that's about the only one I haven't replaced. Then i was told I would experience hard starts and stalling I had niether. Then on my way to work last week in the morning I went to start my lac and nothing just dash lights when I turn the key. Then I got under checked wires on starter all are fine and tightened the battery cables. Still nothing I let it sit about ten minutes and it started. Did the same thing day before yesterday too.could this be the Ignition control module? how do I test it ?
__________________And by lack of power i mean i have to floor it to get up to speed on the highway then let off the gas slowly. someone please let me know what you think i need better gas mileage!

 

codes? Is ignition timing correct? Engine grounds can always be suspect it is located near starter. good luck

 

Are there any codes stored?
How was the cat tested?
Was fuel pressure tested under driving conditions, or just sitting?
Injectors "clicking" doesn't really mean they are actually working properly, tho it does help to know that they are at least making noise.

The ignition modules on GM HEI systems(I'm assuming this is the '90 DeVille?) usually just won't start when hot, or it may cause the engine to just die while driving. Once cooled down, it will allow spark to start the engine again, until it gets hot again. The ignition module will have absolutely nothing to do with whether or not the engine cranks over with the starter. If you are experiencing a no cranking condition, you could have a starter, or starter wiring issue, which may also be tied into the poor running issue.
I'd be looking at all of the power/grounds for the starter system.