90' F150 5.0, fuel running rich, plugs fouling
 

So I recently had my valve gaskets done, bc oil was fouling the plugs. I've been driving with the spout connector off bc the computer causes the timing to go haywire. I believe it needs to be replaced (advice from my mechanic- he fixed another truck, same year/model with similar issues with a new computer) Replaced the plugs when i got the truck back from the shop, ran great for about 4 miles before the plugs fouled again. Now the truck is running super rich, smell fuel on my dipstick, fouling plugs with carbon. Going to replace the FPR next along with the computer, but I imagine it could be the injectors as well. Any advice on what injectors to buy and how difficult it would be to replace them on my own. Or any advice in general would be much appreciated. I'm pretty savvy under the hood. Learning as I go
Fuel pressure and compression all read good
All ignition systems new
new dist timed correctly /wires/plugs
new icm, tps, temp sensor (to ecu)
new valve gaskets
new intake manifold gasket
New alternator
new power steering pump
Crack in both exhaust manifolds, not major