Cadillac Repair: 1994 Cadillac Eldorado, cadillac eldorado, pressure gage

Question
QUESTION: Have a 1994 Cadillac Eldorado ETC.  Just had three coils changed because of intermittent dieing.  Now car surges at times, then sometimes hesitates and sometimes it will die.  It always starts back up on first try, but I am getting no where with the GM repair facility on determining what is wrong.  Have changed fuel filter, no change in performance.  Is it possible that this is the fuel pump?   Repair facility says no codes are showing and they cannot get it to repeat the surge, hesitation or dieing.

Any suggestions on what to check next, or most probable cause is appreciated.   The GM repair facility tells me that they think it might be the PCM or the ignition, but once again, no codes.   They did state that it would be expensive to repair any of these problems.

Help me get my car back to trust worthy operation.

Thank you for your prompt reply.

ANSWER: Did you find your problem ?.

---------- FOLLOW-UP ----------

QUESTION: No.  Still trying to locate.  Thought it might be ignition, no luck.  Now going through sensors one at a time.  This diagnostic is getting expensive as I have had the GM repair facility look at it three different times during the last week.  Each time upon leaving it begins the dying act again.  They repeated tell me they can not duplicate this when they have it.   

Beginning to doubt they want to really determine the problem.   Telling me this is an "old" car.  This old car has been babied with oil changes every 3,000 miles, regular routine maintenance and only has 104,000 miles (2 owner vehicle, 14 with me).

Thanks for any input

Answer
This type of problem which if it is an intermittent problem can be difficult to diagnose if it will not produce the problem all the time.

In such cases as this I always install an external fuel pump pressure gage on the system and tape it to the outside of the windshield so I can monitor the pressure as I drive the car. This way I can tell whether the problem is fuel and or an electrical fault. If the fuel pressure starts to drop off as the car starts losing power this will tell me that you have a fuel pressure problem. If it does NOT drop off then your problem is electrical and we can perform the appropriate test procedures.

Perform this fuel pessure test and let me know what you find out.