Car was purchased new back in '02, no real issues until last year when this started to happen, has 67,310 original miles on it. Car hesitates, no acceleration past 35 mph, problem is getting worse. Actron super AutoScanner gives no code/MIL set. No check engine light alert. Car does not shake or make any noises, seems fine except for the acceleration issue. Car has acted odd a few times upon starting, turned it off, restarted and car was fine. Car died once at a stop light but restarted right away. Problem began months ago with just struggling to get up hills, but now it's bogging down all the time. Here is the list of parts I've replaced to try to fix the problem with no effect.
Spark plugs, spark plug wires, PVC valve, fuel filter, both O2 sensors (upstream & down), coolant temp sensor, EGR valve, upper & lower manifold gaskets (lower did have leak & cleaned inside and out, lower injector O-rings, MAP sensor, throttle body gasket (cleaned inside & out), switched out with good MAF & IAT sensors (no improvement).
Checked fuel pressure - ok
Checked Coils - ok
Checked fuel regulator - ok
All this has had NO effect on the lack of accleration.
Any ideas? Any suggestions?