My 89 Ford E150 van with MPI 5.0 motor surges and will even die when started cold and in Park. By "surge" I mean it revs high for a couple of seconds and then down to a bad stumble and then high again and then back down to barely running. I idles pretty good when warm and even cold, once I put it in Drive, it will run smooth. While in Drive, the idle does seem a little high though.
Compression was good on all 8. With engine warm, I connected a vacuum source to the EGR and it appeared to open and close (stumble with vacuum applied and idled ok when vacuum removed). Has new plugs and wires. Haven't gotten to the new cap and rotor yet, but don't really expect them to help ths problem. Would a vacuum leak run ok Warm? It's a huge pain to try and track vacuum lines on this thing.
Any suggestions appreciated. Thanks, Bobby