Found this:
Service Bullitin
4T40E , 4T45E , 4T65E Surge Slip Condition Under Load in 2nd, 3rd , and or 4th - kw 3.1 automatic body chuggle fourth hesitation hot LG8 miss second shift third valve #PI01385A - (Mar 25, 2004)
4T40E, 4T45E, 4T65E Surge Slip Condition Under Load in 2nd 3rd and or 4th.
Condition/Concern:
The 4T40E/4T45E/4T65E automatic transmission may experience a slip surge condition in second, third and or fourth gears while under load, such as driving up a long hill or mountain. The conditions either separate or working in combination seem to cause the 'Engine Load %' to drop to a value which the PCM commands a lower line pressure (increase in PCS amperage).
'Normal' degradation of MAF over time aggravated by induction of foreign material (fine dust, oil from non-OEM air induction systems; secondly, build up of carbon deposits in combustion chamber/intake valves over time; thirdly, outside ambient temperatures above 95 degrees F(35 degrees C) seem to aggravate the condition.
Recommendation/Instructions:
The MAF should be swapped from a known good unit or replaced and the vehicle evaluated
Clean the top half of engine to remove carbon deposits. Use GM PN 12378546, 3 Step Induction Cleaner Kit, available through GMSPO.The 3 Step Induction Cleaner Kit should be used with tool E-957-001-C available from Auto Tech Industries at 1-800-522-8882 who is the approved supplier of the installation tool. The E-957-001-C kit costs about $595 but has all the adapters to work on TBI and multiport systems and EGR cleaning.
However I'd get a can of CRC Electrical Connector cleaner and open all the connectors, spray them out, let then sit for and hour or so, dry out and reconnect. Also very good for cleaning the MAF
