I have a 2014 Police Interceptor- Utility(I figured the explorer was the most similar- but if I should move this post please direct me to the best spot) . Immediately after an oil change in September I started having problems with my engine. I have been to 4 shops and they have either been stumped or recommended repairs other shops did not feel were necessary/appropriate. I had to stop at a light right on the corner of the shop that did the oil change, when the light turned green my vehicle would not accelerate. I rolled back down onto a frontage road to get out of the way, went and got some staff. Then at restart the engine stalled, check engine light came on, a technician was eventually able to drive it back in, they fiddled with connectors... and took it for a drive and noticed a stutter/driving hard. The next day one of their engine mechanics looked at it - there were no codes and no check engine light. They reported the Mass Air Flow Sensor was not properly connected, they fixed that and didn't look into it any further.

I noticed a stutter/lag while trying to maintain speeds usually between 20-45 varied day to day, and RPM bounces during event. The problem only occurs after driving for awhile and the engine warmed up. I had the check engine light show up after quickly accelerating on the highway mid September. I picked up an in-expensive code reader and had codes for System Too Lean Bank 1 P0171 & Bank 2 P0174 and Catalyst System Efficiency Below Threshold Bank 1 & 2 P0420,P0430. Cleaning the MAF cleared P0420. I replaced the MAF, it did drive a bit better after that; however the issue remained. Tested Purge Valve, it was stuck open, replaced that; I had an increase in felt power, however stutter remained.

Shop 2 said it would be best to start with replacing all sparkplugs and boots, as they were shot. When up in the air symptom couldn’t be re-created, it only occurs while on the road between 25-40mph. Viewed "front" cat with cam- everything looked good, did not view back. They put several hours into trying to figure out the issues however were unable to determine the cause . There were no consistent codes. Overall, it did drive better, but they suggested dealership due to unknown cause of issue.

Shop 3/Dealership said it was the torque converter, recommendation did not seem correct and estimate was over $ 3,000; called shop 2 and Shop 4, both agreed that didn’t sound right.

Shop 4- I went on a lengthy test drive with transmission guy, he did not think it was the torque converter, based off sensations and PIDs. Upon inspection they found the transmission fluid was around a quart and a half low. They cleaned the throttle body as well. After topping up fluid and additive it has been driving better. HOWEVER now the sensation feels like a surge in power rather than a lag or decrease like previously. You can feel it through the accelerator pedal, almost as if I was tapping on it.

I have had a return of the P0430 code.

I do have access to a code reader with live data & graphs(diy level not pro).

Additional history:

There were some pending codes prior to being worked on in July.

P043-00 Catalyst system Efficiency below threshold (bank 2) no sub type info. C1B00-64 Steering angle sensor. U0420-68 Invalid Data received from Power Steering Control Module A- data memory Failure. U3003-16 Battery Voltage. U3003-17 Battery Voltage- Circuit short to ground. U0452-68 Invalid Data Received from Restraints Control Module-Data Memory Failure. They ran the diagnostic again after working on it and there were no codes.

Could it be a computer issue? where would you suggest I look next?

 

For starters, we try to look for what is common to all the codes. Many times it is a poor ground connection that the involved systems share.

It is a little work, but if you remove , clean and reinstall connections coming from the negative battery post to the engine and sheet metal,you might get lucky
It only costs you some time and a little work, but might save you some problems.