[Zixer5]

My 2002 ZX5 is surging under normal acceleration, not hard accel. Almost like someone is out back pushing me. It's a 2.0 DOHC with a A/T, but I know for sure the trans is not the issue because I had the trans replaced with a factory new one about 1500 miles ago. It also did this before the trans swap. Could this be an EGR or maybe TPS issue? Believe it or not, I've had it since new, it has 165,000 miles on it and has never given much trouble, other than one bad tranny. Any guesses?

 

[BC_ZX3]

Surging at part throttle cruising could be a faulty DPFE sensor. The DPFE sensor indirectly controls when the EGR valve opens. Early DPFE sensors were known to be unreliable and were revised by Ford several times over the years in an attempt to increase reliabilty. DPFE sensor replacement would be the cheapest place to start providing there are no other drivability issues, such as inconsistent idling, engine misfire or hesitation, etc.

 

[amc49]

If not at cruise though and under light acceleration then ignition. Possible fuel pump too if it's never been changed. If ignition it may get better with more or deeper throttle, fuel issue will get worse though. These are very sensitive to moderate load ignition, I've chased your issue 2-3 times now and always something afoul in ignition fixed it.

Post above mine is correct as well, you have to determine which condition, cruise or more acceleration you have. DPFEs were pretty good until '02 where Ford shortened the hoses and that lead to water getting in them much much easier. My '02 has the sensor with like 3 foot hoses on it and draped to droop at back of motor open area to make a water trap as I had issues with DPFE as well. I also raised the sensor off the short hoses and ty-wrapped it to the intake plastic hose to make it even higher. Zero trouble since doing so.