The car sat up for 2 months for repair from a rear end hit. Soon after i got it back it quickly go slower and slower on pickup and now it takes15 sec. or more to get to 25mph then hardly reaches 40 or 45mph. The filters were clogged . I changed the 2 fuel filters and drained and change the filter in the tank that had alot of algae. I put diesel and startron to clean it i up and its clean. I cleaned the alda line and banjo bolt and the other line and banjoe that comes from the switchover valve. It has 2 3way vac valves. One line that has a vac of 25 & . comes from the main compressor to booster line & that line goes to the 2 3ways
on top the valve cover. from those one goes to the thermo vac and then egr. 1 other exits the 3way valves and goes to a t that branches off to a dashpot over the (TRANS ) vac valve. and also to the modulator. I tried plugging the line to the thermo vac with no change .1)What vac pressure sould i get from the return line from the 3ways to the tran vac vALVE. WHAT PRESSURE LEADING TO THE MODULATOR, useing a t to check the line.
Should the trans vac valve on the IP hold a vac at all lines that lead to it.
I cant use the car because it goes to slow.
Any suggestions Please.

sounds like your tank filter is cloged. To find out just blow the pick up line back to the fuel tank and see if there's an improvement. It should not be hard to blow. They might have messed up the fuel lines above the differential, kinked, reversed?