cuts off while driving!

[98w_mc]

Hello, I just signed up here, anyway. My 98 aurora drives good on a regular basis, but sometimes in the morning the "check engine light" comes on and the vehicle will shift harder than usual. Also, when the light is on while driving the car will drop down to 500rpm once, come back up, then go all the down and cut off leaving me to steer a 4000lb. car myself in turns or where ever I happen to be. I went to my mechanic recently and found a good deal of codes on the scanner, i'll put them below. If you had similar issues and solved the problem please reply, it runs fine today, but I don't know what to expect tommorow morning. Here are the codes:

P0101-Mass airflow circuit out of range
P0300-random cylinder misfire
P0463-fuel level sensor ckt signal high/open
P1533-a/c evap temp sensor voltage high---a/c doesn't work, yet heater works great
P1537-a/c request circuit voltage low
P1599-cc power mgmt mode or eng stall
P1617-engine oil level switch circuit

We cleared all the codes and the mechanic drove with me using the scan tool and nothing reappeared, but in the morning on a cold idle the random misfire came back. Oddly, we unclipped the mass airflow sensor during the rough idling and the engine ran smoothly, but after trying a different MAS it still ran rough in the morning, so now I'm perplexed and will probably go to the expensive GM dealer, but I wanted to see what everyone thought of it first. Thanks.

[emundorf]

Crank position sensor. I had the same problem where the engine/tach would just drop off momentarily and usually come back on. Sometimes though, the engine would completely shut off. Make sure you replace both sensors. I have an '01 4 liter, but I'm assuming yours would be similar. Good luck, and I hope this works!!!

[98w_mc]

Thanks for your help, I will look into the crank sensor. Also, does anyone know what would cuase the fuel gauge to float around during driving. Drops when accelerating and levels off during stops.

[Smoothe LJ]

Originally Posted by 98w_mc

Thanks for your help, I will look into the crank sensor. Also, does anyone know what would cuase the fuel gauge to float around during driving. Drops when accelerating and levels off during stops.

Well im no expert but i do know that there is a floating handle on the fel pump that give tha gauge it's reading so there probably something to do wit tha fuel pump

[Indy8]

If you have the means to get it fixed at the dealer, do it. Yes it sucks, but how do you put a price on weeks of frustration and only half the problem solved.

[98w_mc]

Thanks for your suggestions.

Does anyone know of any modifications that are good for the 4.0 northstar?

[Awood14]

I dont know if you've gotten the problem fixed yet, but I had the same thing happen to me. I have a 98' and the engine would just cut off during driving. I found that I could drive at higher speeds no problem, but once I got to about 1000rpms, the tach would drop to 0 and the engine would cut off. And the logner I drove, the more frequently it would happen. I would actually have to rev the engine in nuetral, and put it into gear just to stop it from stalling. Anyway once the Air Flow Regulator was replaced, it ran good as new.