WOT lack of RPM

[Cwescott]

Recently got 2001 Challenger 1800 with the Mercury M2 240 EFI power plant back together and running. For starters had to some excessive adjusting I feel to the idle screw to keep running around 900-1100 rpms and when WOT only achieving 3900 -4100 rpms and about 15-20mph. Compression is within in spec on all but one cylinder not enough for me to worry. Spark on all 6 cylinders and verified throttle is in fact opening all the way at WOT. Checked fuel filters and pulled apart vapor separator no issues there. I am having quite of bit of excess fuel exit vapor separator vent lines. Contemplating sending out injectors for cleaning service and pulse check. Anything else I can cross off the list of potential issues would love to get running right before the weather turns.
Thanks

 

[Tim75]

Check fuel pressure and ignition timing.

I had my injectors serviced a year ago. I wish I had had it done 10 years ago.
Better performance, less smoke, better fuel economy.