I have a 1999 SR5 4X4 V6. Started out last week with engine hesitation (like a studder) on initial throttle application and around 2k rpm, only the gentlest of throttle application would rev the motor with out the studder (the check eng light has never illuminated). Replaced the MAF sensor, replaced the plugs with NGK Iridum's, plug wires were replaced, and I cleaned the throttle body.
It ran great for about three days, now it has developed a rough idle. Once the rpm's drop below 1K it feels like it's about to die. The motor drops momentarially below 500 and then will shoot back up to 1K. Replaced the Fuel Filter today, and that had no effect on the problem.
Has anyone else ran into this particular problem? I was thinking of doing the voltage check on the fuel pump and then perhaps change out the fuel pressure regulator but I would greatly appreciate any advice, especially if you have seen this before.
Thanks!