Hi

This is my first post because of a problem with my daughters car. Here are the specifics below:

2000 Pontiac Sunfire 2.4 automatic
Revs good in park and neutral
Hesitates when shifted into drive but eventually will accelerate
If stopped in the middle of the hill it hesitates unless it is put in neutral or manually downshifted


Here is the kicker. You can drive the car up a hill with absolutely no problems or hesitation in REVERSE

We have tried the following
Plugs, coils, O2 sensor, TPS, New ECU, Wires Reporgrammed the ECU
No SEL and the no bad readings when hooked up to a diagnostic machine.

Any help/recommendations would be appreciated.

Thanks
Joe

Have you checked vaccum readings yet?

My brother said he did a smoke test on the vacuum

Update: Smoke test was done on the emission system they used a sniffer and a propane tester on the vacuum lines

I also wondered what the vacuum readings are. and would the needle shake properly?
It might idle good in park and neutral, but there's also more fuel demand in the forward gears, and going uphill. Probably more
electrical drain too.

Do you have access to the obd diagnostic to get the live data stream while it's hesitating up the hill?

is this something an auto transmission could do?
does the auto transmission need vacuum lines?
If transmissions could do this hesitation, would the obd pick it up?
just thinking of more questions for anyone