Engine surges and does not transfer power into speed

[Rjj]

I verified the following:

MAF
TPS
tranny's modulator/diapham

I received no codes (recently reset computer) with KOEO.

I received two codes 412 and 538 with KOER.

412 - Cannot control RPM during Engine Run Self-test -- High RPM check

538 - Insufficient RPM change during Dynamic Response Test (Engine Run Self-test)

538 also means a few other things but the combo of 412 and 538 I pick the RPM one because they are related.

I do notice when I push on the gas a let up completely, the engine continues to ramp slowly back down to idle rather than quickly responding. Is this normal? I tested the TPS on a scope and it worked perfectly. However, the source voltage is 4.8v instead of 5volts. Can this be adjusted?

I don't know what to do next??? It does run but getting to highway speeds is like driving a four banger!

Any ideas?

SpeedSter240EFI
Rj

 

[mdrut]

9 out of 10 surges can be traced to vacuum..Have you changed anything recently?? Could there be a broken "T" or a line off or burned in 2??? Start with the basics, the slow drop is normal.