99 E300 DT No Start

[99/05 Benz]

Had installed six new glow plugs, new MAFS in the last four months. Ran fine, except for a little lag around 1,500 RPM.

Noticed a hard start problem when hot recently. Went to deaelr they had it for two days and finally said it needs a starting module $1,200.00 but it will continue to start. It will nor start eventually.

Left the garage door open a few nights ago, went down to start and it just cranked, almost started then cranked. Heated up the fuel lines, filter and block . After a few minutes it started, figured it gelled up.

Two days later went to start the car almost turned over then just cranked. Changed the filter, almost started then just cranked.

Can't seem to see any air in the clear fuel lines and car has plenty of fuel in it.

Glow plug light comes on normal and goes off normal. Could be a coincidence that the module went the same time I left the door open, I guess.

Any dieas?