surging at idle and steady cruise, looking for suggestions
 

93 R1, 80k miles, engine rebuilt ~4k ago. Car has been running well, just started developing a surging idle (bounces between 700 and 1300 intermittantly, other times rock steady at 850). While idle was bouncing, I checked the power fc, saw that the injector duty cycle was bouncing between 5.5% and 0%.

Additionally, I've had an issue with blowing fuel pump fuses. The first time was after an autox run, left the engine running in grid, pulled out for 2nd run, car stalled on the way to the start line. 2nd time was driving home from the autox, cruising the highway, downshift to 3rd to pass a car, got around the car and car dies again ... coast to a stop and fuse blown again.

Mods:
power FC, base map set by SR Motorsports based on mods on car
downpipe
catback

I'm thinking about replacing fuel pump (because of the blown fuse), fuel filter (because it's been ~20k miles, but ~8 years), and pulsation dampener. Any other thoughts of what to check / test before just replacing parts?

The following WILL ONLY work if you dont have a vacuum leak anywhere passed the Throttle body


Do this my friend.
1. Remove the intake platic piece that attaches to the throttle body
2. Remove the air hose that is attached to the side of that same plastic intake and pull it back as far out of ur way as possible.
3. Loosen the TPS one screw bolt on top and one screw bolt on the bottom if you cant get to them then remove the throttle body through the 4 12mm nuts keep the coolant hoses on. - Just pull it out towards you and turn it slightly to the left.
4. Reinstall Throttle body with the tps now slightly loose.
5. Bring the TPS all the way down pointing down. - (The lower it is th ehigher the Voltage and RPM)
6. There is a little tiny screw called the fast idle screw is infront of the TPS on the Throttle body lossen it a few turns
7. Find the air bleed screw on the bottom of the throttle body you can use a flat head and turn it leftly loosy
(NOW TURN YOUR CAR ON) IT WILL IDLE prolly around 2k to 3k rpms with some hunting and droops but it will stay idling)
8. NOW... all you need to do is lower the idle as needed.
9. First retighten up the fast idle screw the tighter it is the lower the rpms becuase it restricts air from the bottom flap of the intake.
10. Adjust the TPS with the use of a voltmeter. check instructions here.
http://www.rx7.org/Robinette/tps_adj.htm make sure the all measurements are witn in spec. The lower the voltage the less open the throttle.
11. play around with the air bleed screw to adjust the throttle as needed.

P.S. I would have someone inside the car yelling the rpm level as you adjust them.